chrome-debug-mcp
chrome-debug-mcp
chrome-debug-mcp 是一个基于 Rust 的异步 Model Context Protocol (MCP) 服务器,它允许 AI 代理和大语言模型通过 Chrome DevTools Protocol (CDP) 原生地控制、自动化和调试基于 Chromium 的浏览器。
底层使用 cdp-browser-lite(它本身重新导出了 cdp-lite 客户端),这个 MCP 服务器直接挂接到浏览器,避免了繁重的抽象,使你能够直接从编辑器或聊天界面进行实时调试会话。从 v0.2.0 开始,它还可以自动管理 Chrome 进程的生命周期。
✨ 功能特性
该服务器原生实现了一套按 CDP 域和原生进程管理分类的工具:
🛡️ 隐私与安全
隔离配置文件(默认):每次 MCP 服务器启动 Chrome 时,它都会在系统的临时目录中创建一个全新的临时用户配置文件。该配置文件与你的主浏览器配置文件完全独立,并且会在浏览器停止时被删除——一个会话中的 cookies、历史记录、已保存的密码或会话数据绝不会泄漏到下一个会话。
类似无痕浏览的体验:默认情况下,来自你个人账户的 cookies、历史记录、已保存的密码或会话数据都不会与受管实例共享。
身份保护:即使 LLM 完全控制浏览器,它也无法访问你已登录的会话(例如 Google、GitHub、银行)或冒充你,除非得到明确授权。
用户配置文件模式:使用
--user-profile标志,通过你的现有系统配置文件启动 Chrome。当你希望 LLM 在你活跃的会话(cookies、已保存的登录信息等)中工作,而无需在每个站点重新认证时,这非常有用。请谨慎使用,因为这会让 LLM 访问你的个人浏览器数据。⚠️ 关于
--user-profile的说明:由于 Chrome 的单例架构,如果你的浏览器已经打开,它会委托该请求并无法打开调试端口。你必须在启动 MCP 之前关闭所有现有的 Chrome 实例,或者使用--remote-debugging-port=9222标志手动启动浏览器。
🚀 Chrome 实例与标签页管理
多实例支持:在动态端口上生成并控制多个并发、独立的 Chrome 进程,每个进程都有自己的隔离配置文件目录。使用
--max-instances标志限制实例数量。实例注册表工具:使用
open_instance、list_instances和close_instance来创建、审计和清理额外的实例。所有现有工具都接受可选的instance_id参数,以将命令路由到目标浏览器。多标签页支持(新):在单个 Chrome 实例中控制多个并发标签页,通过单个 WebSocket 连接多路复用事件流和命令。
自动发现:由目标页面打开的弹出窗口(例如
window.open())会被自动发现、附加并注册到会话的标签页注册表中。缓存隔离:状态缓存(控制台消息、网络流量、调试器解析的脚本、WebMCP 工具)按标签页严格隔离,因此事件不会跨目标泄漏。
标签页注册表工具(新):
open_tab— 打开一个新标签页,可选地带有自定义标签和目标 URL。返回包含tab_id的 JSON,以便在其他工具中复用。list_tabs— 以 JSON 形式列出该实例所有已打开并注册的标签页(tab_id、label、target_id、url),以及当前活动标签页。当没有注册标签页时,工具会回退到实例的默认单标签页连接。close_tab— 按 ID 关闭特定标签页并清理其缓存状态。返回新的活动标签页。switch_tab— 更改在工具调用中省略tab_id时使用的默认活动标签页,并可选择将其置于前台。
对 LLM 友好的接口:生命周期工具(
open_instance、close_instance、open_tab、list_tabs、switch_tab、close_tab)返回结构化 JSON,因此代理可以链接调用而无需用正则表达式解析文本,并且它们的描述遵循标准 MCP 模板(副作用、前提条件、返回值、替代方案),以便模型正确地对它们进行排序。目标路由(新):所有标签页级工具都接受可选的
tab_id参数,以将命令定向到特定标签页并从中检索缓存状态。如果省略,则默认以活动标签页为目标。隔离配置文件:默认使用全新的临时配置文件启动 Chrome,确保它不会与你的主浏览器共享 cookies、密码或会话数据。
用户配置文件支持:可选地使用
--user-profile来利用你现有的浏览器会话和 cookies。动态端口管理:自动检测默认端口(9222)是否已被占用。
如果该端口被一个暴露 CDP 的 Chrome 实例(用户启动的或另一个受管的
chrome-debug-mcp实例)占用,它会自动附加到该实例,而不是生成一个新的实例。受管配置文件是临时的,因此不存在持久的按端口状态;共享同一端口的第二个服务器只是共享同一个浏览器(并且绝不会杀死已附加的实例)。
Docker 与无头模式支持:与 Docker 环境完全兼容。使用
--headless标志在容器内运行没有 GUI 的 Chrome。远程/主机连接:使用
--host参数连接到运行在另一台机器或主机上的 Chrome 实例(例如,从容器内使用--host host.docker.internal)。可选的自动化信息栏:添加
--enable-automation标志以显式显示原生的“Chrome 正受到自动化测试软件控制”消息。默认情况下,此功能被禁用,以实现更隐蔽的交互。代理支持:
restart_chrome现在接受可选的proxy_server参数,以启动 Chrome 并通过代理路由流量。自动启动:自动检测 Chrome 是否在指定端口上运行。如果没有,它会使用所需的标志生成一个新实例。
restart_chrome:重启受管的 Chrome 实例。能力预设:
restart_chrome接受可选的features数组,以便客户端可以在每次重启时选择加入额外的浏览器能力。它是一个封闭集合——故意不接受任意的 Chrome 标志,以防止该工具成为命令行注入点:WEB_MCP— 启用实验性的 WebMCP 表面(--enable-features=WebMCPTesting、--categoryExperimentalWebmcp=true),适用于向浏览器暴露工具的网站。WEBGL_SOFTWARE— 强制使用 SwiftShader 软件 WebGL(--use-gl=angle、--use-angle=swiftshader、--enable-unsafe-swiftshader),适用于无 GPU 的环境,例如容器。
预设适用于该调用启动的实例;之后省略
features的restart_chrome会清除它们,这与proxy_server的行为方式一致。stop_chrome:优雅地关闭受管的 Chrome 实例(SIGTERM/SIGINT,回退到 SIGKILL)。健壮的生命周期:修复了 Chrome 进程悬挂的问题。临时配置文件会在停止时被删除,
cdp-browser-lite会清理因突然终止而遗留的孤立配置文件目录;通过启动标志和配置文件修补,抑制了“Chrome 未正确关闭”的恢复气泡。⚠️ 行为变更:受管的 Chrome 实例现在会在 MCP 服务器进程退出时被终止(包括崩溃)。以前,受管的 Chrome 在服务器崩溃后仍然存活,并在重启时重新附加;从现在起它会被杀死。已附加的(用户启动的)Chrome 实例永远不会被杀死。
🔐 代理认证
enable_proxy_auth:通过挂接到FetchCDP 域并提供用户提供的凭据(用户名和密码),自动处理代理认证挑战。健壮性改进:现在为较慢的住宅代理提供 30 秒超时,并且默认只拦截
Document请求,以防止破坏后台请求。预热:自动导航到
prewarm_url(默认为http://api.ipify.org?format=json),以便在你的主要导航任务之前可靠地建立代理隧道。你可以选择将拦截限制为特定的resource_type。
🖱️ 用户输入
click_element:通过使用 CSS 选择器模拟对特定元素的原生鼠标点击。它计算元素的中心坐标并直接分发 CDP 鼠标事件。fill_input:用指定的文本填充 DOM 中的输入字段。它通过 CSS 选择器聚焦元素,然后使用原生 CDPInput.insertText。scroll:按像素、视口高度(页)滚动页面,或滚动到特定元素。对于与懒加载内容或无限滚动交互至关重要。
📡 网络检查
get_network_logs:检索拦截到的网络请求(REST/HTTP)和 WebSocket 帧。高级过滤:按 URL、资源类型、WebSocket 方向或负载内容过滤日志。
负载检查:访问完整的请求/响应头、REST 响应体和 WebSocket 帧。
上下文优化:可选的“摘要模式”,避免淹没 LLM 的上下文窗口。
🪵 控制台与错误
get_console_logs:从浏览器检索控制台日志。这包括 console.log/warn/error 调用、异常和网络错误。对于排查页面脚本和错误至关重要。包括可选的日志级别过滤和clear标志,以高效管理状态。
⚡ 性能与剖析
get_performance_metrics:从浏览器检索运行时性能指标(例如,JS 堆大小、DOM 节点数、布局持续时间)。有助于快速获取页面内存和计算开销的快照。profile_page_performance:记录并分析页面的性能跟踪。它会自动计算 Core Web Vitals(FCP、LCP、DCL、Load)并识别最长的 Long Tasks(主线程阻塞操作)。你可以选择在禁用缓存的情况下重新加载页面,以模拟冷启动。
🌐 页面与运行时控制
capture_screenshot:截取当前页面(或完整页面布局)的屏幕截图,并将其作为 base64 编码的图像块返回给 LLM 客户端。navigate:将活动标签页导航到特定 URL。reload:重新加载当前页面。inspect_dom:获取整个 HTML 或围绕搜索查询的智能片段。上下文搜索:搜索特定文本,并获取其周围可配置数量的字符。
Token 效率:大幅减少大型页面的上下文窗口使用量。
evaluate_js:在页面上下文中全局运行任意的 JavaScript 表达式。
🐞 实时调试与执行控制
pause_on_load: 启用调试器并触发页面重新加载,在解析到的第一条脚本语句处暂停执行。search_scripts: 在所有已解析的脚本上下文中搜索查询,以精确定位断点的行和列。set_breakpoint: 使用script_id、url或精确的script_hash设置精确的 JS 断点。evaluate_on_call_frame: 直接在当前暂停的调试器调用帧的局部作用域内计算 JavaScript 表达式。step_over: 单步跳过下一条表达式语句。resume: 取消暂停并恢复执行。remove_breakpoint: 移除先前设置的断点。
🧩 WebMCP(页面暴露的工具)
需要使用 WEB_MCP 能力预设重启 Chrome(参见 restart_chrome)。
webmcp_list_tools: 列出当前页面暴露给浏览器的工具(名称、描述、inputSchema、frameId)。webmcp_invoke_tool: 按名称调用页面工具。input是一个 JSON 对象字符串(例如"{}"或"{\"product\":\"knot\"}"),需与工具的inputSchema匹配。最多阻塞等待结果 30 秒。webmcp_get_invocation: 按invocationId返回调用的状态(Pending/Completed/Error/Canceled)和结果——非阻塞。webmcp_list_invocations: 列出会话中所有调用的状态,可选用status过滤。⚠️ 同意对话框:具有副作用(剪贴板写入、表单提交等)的页面工具可能会显示一个需要人工点击的页内确认对话框。在这种情况下,
webmcp_invoke_tool会返回一个包含invocationId的超时错误——该调用保持Pending状态(绝不会被取消),因此你可以在用户批准或拒绝后使用webmcp_get_invocation轮询它。
🧪 稳定性与可靠性
广泛的单元测试:全面的测试套件,确保事件处理和工具反序列化的可靠性,尤其是在
debugger领域。无副作用测试:所有单元测试都设计为隔离运行,不启动真实的 Chrome 实例,也不修改文件系统。
内部重构:通过 trait 和依赖注入解耦核心逻辑,确保长期可维护性。
Related MCP server: chrome-devtools-mcp
⚙️ 配置
默认情况下,MCP 服务器通过 cdp-browser-lite 的跨平台搜索来发现 Chrome 可执行文件:首先查找 CHROME_PATH(绝对优先级),然后查找 PATH 中的常见二进制文件(google-chrome、google-chrome-stable、chromium、chromium-browser),最后查找操作系统特定的位置(macOS 上的 /Applications/Google Chrome.app/...、Windows 上的 chrome.exe 安装目录、Linux 上的 /usr/bin/google-chrome、/opt/google/chrome/chrome 和 /snap/bin/chromium)。这是服务器先前硬编码路径的严格超集。
参数:
--local: 仅将导航限制为本地地址(localhost、127.0.0.1、192.168.x.x或*.local)。出于安全考虑,强烈推荐。--headless: 以无头模式运行 Chrome(无 GUI)。对于 Docker 或服务器环境至关重要。--user-profile: 使用默认的系统用户配置文件(会话、Cookie 等),而不是全新的配置文件。这对于在研究会话期间避免重复登录非常有用。--host: 指定 Chrome 实例的目标主机(默认:127.0.0.1)。使用host.docker.internal从容器连接到宿主机。--port: 指定远程调试端口(默认:9222)。--enable-automation: 启用“受自动化软件控制”的信息栏。--max-instances: 限制并发 Chrome 实例的最大数量(默认:8)。如果设置了--user-profile,则忽略此参数。
环境变量:
CHROME_PATH: 显式定义 Chrome 可执行文件的路径。
🐳 Docker 与无头模式用法(v1.0.0)
chrome-debug-mcp 完全支持容器化。这为 LLM 提供了几种强大的用例:
1. 云部署(通过 Glama)
使用此服务器的最简单方式。Glama 会生成一个预装了 Chrome 的 Docker 容器。LLM 无需任何本地设置即可立即访问云中的浏览器。
2. 隔离的本地使用
在 Docker 中运行所有内容,避免在宿主机上安装 Chrome 或 Rust:
docker build -t chrome-mcp .
docker run -i --rm chrome-mcp --headless3. 混合模式(容器控制宿主机)
MCP 服务器在安全的 Docker 容器内运行,但控制你实际桌面上的 Chrome 实例。这使 LLM 能够在你的真实浏览会话中为你提供帮助:
使用以下参数启动本地 Chrome:
--remote-debugging-port=9222注意:如果在此模式下需要代理支持,你还必须使用
--proxy-server="http://your-proxy:port"标志启动 Chrome。
运行容器:
# On macOS/Windows
docker run -i --rm chrome-mcp --host host.docker.internal🚀 快速开始
以原生方式安装和运行 MCP 服务器的最简单方法是通过 Rust 的 Cargo 或下载预编译的二进制文件。你不再需要手动启动 Chrome,MCP 服务器将自动启动一个带有正确调试标志的可见 Chrome 实例。
1. 安装
选项 A:预编译二进制文件(推荐)
前往 Releases 页面,下载适用于你平台(macOS、Windows、Linux)的原生可执行文件。我们为 Windows 提供 .msi 安装程序,为 UNIX 系统提供 shell 脚本。
选项 B:通过 Cargo 安装
cargo install --git https://github.com/raultov/chrome-debug-mcp选项 C:通过 Shell 脚本安装(Unix)
curl --proto '=https' --tlsv1.2 -LsSf https://github.com/raultov/chrome-debug-mcp/releases/latest/download/chrome-debug-mcp-installer.sh | sh2. 配置你的 MCP 客户端
此服务器已经过全面测试,并确认可与 Claude Code、agy 和 codex 配合使用。使用以下任一模式配置你的 AI 客户端以执行服务器。
通用配置(JSON)
大多数 MCP 客户端(如 Claude Code 或任何基于 JSON 的配置)使用此结构。以下是三种主要使用模式:
{
"mcpServers": {
"chrome-debug-mcp": {
"command": "chrome-debug-mcp",
"args": [],
"env": {}
},
"chrome-docker": {
"command": "docker",
"args": ["run", "-i", "--rm", "chrome-debug-mcp:v1.0.9", "--headless"]
},
"chrome-docker-hybrid": {
"command": "docker",
"args": [
"run",
"-i",
"--rm",
"--net=host",
"chrome-debug-mcp:v1.0.9",
"--host",
"127.0.0.1"
]
}
}
}注意:在 Linux 上,使用 --net=host 的 chrome-docker-hybrid 模式是推荐的方式,可让容器访问你在 127.0.0.1 上的本地 Chrome 实例。
Claude Code
要在 Claude Code 中添加并激活服务器:
claude mcp add chrome-debug-mcp chrome-debug-mcp3. 使用
连接后,AI 代理将在执行第一条命令时自动处理启动 Chrome 的操作。浏览器将保持可见,以便你可以直观地跟踪调试过程。
4. 代理工作流与多实例指南
LLM 可以使用几种优化模式来操作此服务器:
A. 隔离的多实例场景
在运行自动化浏览器会话时,你可以启动独立的 Chrome 进程,以防止 Cookie 污染或标签页冲突:
调用
open_instance,并传入label: "user-session-1"或可选的代理服务器配置。这将返回一个唯一的instance_id(例如chrome-2)。将
instance_id显式传递给下游工具,如navigate、evaluate_js或webmcp_list_tools。完成后使用
close_instance清理资源。
B. 使用 WebMCP
如果你导航到支持 WebMCP 的页面(例如 https://www.knot.kz/#/agent-tools):
可以使用
webmcp_list_tools获取网页注册的工具。默认情况下,出于安全考虑,
WEB_MCP处于禁用状态。如果工具列表为空,请调用restart_chrome并传入features: ["WEB_MCP"],然后执行reload。使用
webmcp_invoke_tool调用页面工具,并提供输入 JSON 参数。如果同意对话框暂停了网页上的执行,工具将在 30 秒后超时,但会保持调用挂起状态。你可以使用webmcp_get_invocation轮询其结果。
🛠 编译(从源码)
如果你想从源码编译:
git clone https://github.com/raultov/chrome-debug-mcp
cd chrome-debug-mcp
cargo build --release生成的二进制文件将位于 target/release/chrome-debug-mcp。此项目利用 cargo-dist 通过 GitHub Actions 无缝处理跨平台原生分发。
📖 为什么选择此 MCP 服务器?
其他集成服务器(如 Puppeteer/Playwright 包装器)是高层级的、重量级的,并且通常无法暴露真实的、可交互的逐步调试器。此 MCP 服务器使用原始 CDP 消息,将其 1:1 映射到 LLM 工具,使智能代理能够真正地单步跳过 JS、原生读取局部作用域变量、在 V8 编译器上下文中搜索,并准确理解脚本崩溃的原因。
📜 许可证
此项目根据 MIT 许可证 授权。有关更多详细信息,请参阅 LICENSE 文件。
Available Tools
30 toolscapture_screenshotA
Captures a visual representation of the current page viewport or entire page as a base64 encoded image ('full_page' defaults to false, capturing only the visible viewport; set true to capture the entire page). Side effects: none (read-only). Prerequisites: requires an active Chrome tab. Returns: base64 encoded image in specified format. Use this to visually verify UI state, layout, or rendering. Alternatives: 'inspect_dom' for raw HTML structure, 'get_performance_metrics' for rendering metrics.
| Name | Required | Description | Default |
|---|---|---|---|
| format | No | Output image format. Constraints: must be 'png', 'jpeg', or 'webp'. Interactions: 'quality' applies only to 'jpeg' and 'webp' formats. Defaults to: "png". | |
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| quality | No | Compression quality (0-100, higher=better quality). Constraints: integer between 0 and 100. Interactions: only applies when 'format' is 'jpeg' or 'webp'; ignored for 'png'. Defaults to: 100. | |
| full_page | No | Capture the entire page beyond visible viewport. Constraints: boolean value. Interactions: if true, captures full page height; if false, captures only visible area. Defaults to: false. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It explicitly states 'Side effects: none (read-only)', the prerequisite of an active Chrome tab, and the return type (base64 encoded image). It also clarifies the full_page behavior. This is exceptionally transparent for a tool without annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is compact yet structured with clear labels (Side effects, Prerequisites, Returns, Alternatives). Every sentence earns its place, and there is no filler or repetition beyond a minor but acceptable mention of base64 in the first and Returns sentences.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
This is a mutating? no, read-only tool with no output schema and no annotations. The description covers side effects, prerequisites, return value, common use case, and alternatives. For a screenshot tool with 5 optional parameters and no output schema, this is complete enough for an agent to call it correctly and interpret the result.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100% with each parameter already providing defaults, constraints, and interactions. The description adds no new parameter-level meaning beyond what the schema states—it only mirrors full_page behavior and mentions base64 output. Per the rubric, baseline 3 applies when the schema does the heavy lifting.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb ('Captures') and resource ('visual representation of the current page viewport or entire page'), and states the output as a base64 encoded image. It also explicitly names alternatives (inspect_dom, get_performance_metrics), making the tool's unique purpose clear.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description explicitly states when to use the tool ('Use this to visually verify UI state, layout, or rendering') and provides alternatives with their specific use cases ('inspect_dom for raw HTML structure', 'get_performance_metrics for rendering metrics'). It also notes the prerequisite of an active Chrome tab, giving clear operational context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
click_elementA
Triggers a native mouse click event on a DOM element identified by CSS selector, executing click handlers and form submissions. Side effects: may trigger page navigation, form submission, or modify DOM state. Prerequisites: element must exist and be visible (getBoundingClientRect must return valid coordinates). Returns: success confirmation with click coordinates. Use this to interact with buttons, links, checkboxes. Alternatives: 'fill_input' for text input, 'evaluate_js' for complex interactions.
| Name | Required | Description | Default |
|---|---|---|---|
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| selector | Yes | CSS selector identifying the target element. Constraints: valid CSS selector string matching a single DOM element. Interactions: must resolve to exactly one visible element or operation fails. Defaults to: None (required). | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of disclosure. It clearly lists side effects (page navigation, form submission, DOM state change), prerequisites (visibility), and the return value (click coordinates). This is comprehensive and does not contradict any structured data.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is three purposeful sentences, front-loaded with the main action and side effects, with no filler or repetition. Every sentence contributes value.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description covers purpose, side effects, prerequisites, alternatives, and return value. With no output schema, it explains what to expect (click coordinates). For a click tool, this is complete; nothing an agent needs to call it correctly is missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the baseline is 3. The description does not add new meaning to the parameters themselves; the only extra context, the selector mutability constraint, is already present in the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific action ('triggers a native mouse click'), identifies the resource ('DOM element identified by CSS selector'), and notes the effects ('click handlers and form submissions'). It also distinguishes from siblings by naming alternatives like fill_input and evaluate_js.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It explicitly lists the intended use cases (buttons, links, checkboxes) and names the alternative tools for text input and complex interactions, giving clear routing. It also mentions the prerequisite that the element must exist and be visible.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
close_instanceA
Closes and stops the specified Chrome instance by id. Side effects: destructive - for secondary instances the Chrome process is terminated and the instance is fully removed from the registry; for 'default' the process is stopped but the registry entry is kept and the instance is re-created lazily on the next tool call. Returns: structured JSON with the instance_id and whether it was removed from the registry. Use this to free resources used by sessions created with 'open_instance'. Alternatives: 'stop_chrome' to stop an instance, 'close_tab' to close a single tab.
| Name | Required | Description | Default |
|---|---|---|---|
| instance_id | Yes | The instance id to close. The 'default' instance cannot be removed: it is stopped and kept (re-created lazily on next use); all other instances are fully removed. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It explicitly describes side effects (destructive for secondary instances, special handling for 'default') and the return format (structured JSON with instance_id and removal status). No behavioral aspect is left undocumented.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is thorough yet every sentence serves a purpose: core action, side effects, return value, usage context, and alternatives. It is front-loaded with the primary verb and resource, and the logical progression aids comprehension without any filler.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
This tool has nuanced behavior (different outcomes for default vs. other instances) and no output schema, yet the description covers all necessary context: side effects, return structure, when to use it, and alternatives. An agent can invoke it correctly without needing additional information.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema description covers 100% of the single parameter, including the critical difference between 'default' and other instances. The description does not add parameter-level detail beyond the schema, so a baseline score of 3 is appropriate. The contextual reinforcement in the description is helpful but redundant with the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action: 'Closes and stops the specified Chrome instance by id.' It also distinguishes itself from siblings by naming alternatives like stop_chrome and close_tab, so an agent can immediately understand what this tool does that others do not.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides explicit usage guidance: 'Use this to free resources used by sessions created with open_instance.' It also lists alternatives with their distinct purposes, making it unambiguous when to call this tool versus stop_chrome or close_tab.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
close_tabA
Closes a specific tab by its registered Tab ID. Side effects: destructive - removes the tab from the registry and closes it in Chrome; if it was the active tab, another registered tab becomes active. Prerequisites: the tab must exist (see 'list_tabs'). Returns: structured JSON with the closed 'tab_id' and the new 'active_tab_id' (null when no tabs remain). Use this to clean up tabs you no longer need. Alternatives: 'close_instance' to stop a whole Chrome instance.
| Name | Required | Description | Default |
|---|---|---|---|
| tab_id | Yes | The Tab ID of the tab to close (e.g. 'tab-1'). | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full disclosure burden. It discloses side effects (destructive, removes tab from registry, closes in Chrome, active tab handling) and return value structure. This is comprehensive and goes beyond minimal requirements.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is structured logically: purpose, side effects, prerequisites, return, usage, alternative. It is appropriately sized with no redundant sentences, and the core purpose is front-loaded.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool with two parameters (one required) and no output schema, the description explains the return value, side effects, and usage guidance sufficiently. It also integrates with sibling tool context, making it complete for an agent to invoke correctly.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the schema itself fully documents both parameters. The description adds some context (e.g., prerequisite of tab existing) but does not provide additional parameter-level semantics beyond what the schema already states, aligning with the baseline of 3.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific verb and resource ('Closes a specific tab by its registered Tab ID') and differentiates from sibling tools like 'close_instance' by explicitly naming it as an alternative. This makes the tool's purpose unmistakable.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It clearly indicates when to use the tool ('Use this to clean up tabs you no longer need'), states prerequisites ('the tab must exist (see 'list_tabs')'), and names the alternative ('close_instance' to stop a whole Chrome instance). This explicitly guides selection among siblings.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
evaluate_jsA
Executes arbitrary JavaScript code in the page context, returning evaluated results as JSON-serializable values. Side effects: may modify DOM, state, or trigger network requests. Prerequisites: requires an active Chrome tab; script context must allow execution. Returns: JSON-serialized return value (or error if promise rejected). Use this for dynamic inspection, DOM manipulation, complex interactions. Alternatives: 'inspect_dom' for read-only DOM queries, 'click_element' for UI interactions.
| Name | Required | Description | Default |
|---|---|---|---|
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| expression | Yes | JavaScript code expression to execute. Constraints: valid JavaScript (single expression or IIFE). Interactions: automatically awaits promises; 'returnByValue' returns serialized results. Defaults to: None (required). | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It discloses side effects (may modify DOM, state, trigger network requests), prerequisites, return behavior (JSON-serializable values, error on promise rejection), and context requirements. This is comprehensive, though it omits details like potential CSP restrictions or permission scopes, leaving a small gap.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is dense but every sentence earns its place: purpose, side effects, prerequisites, return, usage, and alternatives. It is well-structured and front-loaded with the core purpose, though the inclusion of both prerequisites and usage could be slightly streamlined without losing value.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a side-effect-capable tool with no annotations or output schema, the description covers all essential aspects: what it does, side effects, prerequisites, return format, error handling, and distinctions from siblings. It does not go into error specifics or permission nuances, but it is sufficient for an agent to invoke it correctly in most scenarios.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Input schema coverage is 100%, with each parameter documented. The description adds minimal extra meaning: it mentions that promises are awaited, but the schema already states this. It does not elaborate on tab_id or instance_id beyond what the schema provides, so the baseline 3 applies as the description relies on the schema for parameter semantics.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool's action — "Executes arbitrary JavaScript code in the page context" — with a specific resource (JavaScript) and context (page). It immediately distinguishes its purpose from read-only inspection and UI interaction by naming alternatives, ensuring an agent can identify its niche.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides explicit guidance: "Use this for dynamic inspection, DOM manipulation, complex interactions" and lists concrete alternatives ('inspect_dom' for read-only queries, 'click_element' for UI interactions). It also states prerequisites (active Chrome tab, script context must allow execution), giving clear when-to-use and when-not-to-use conditions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
evaluate_on_call_frameA
Evaluates JavaScript expressions within the scope of a paused call frame, accessing local variables and call stack. Side effects: read-only by default; can modify state if expression includes mutations. Prerequisites: requires debugger to be paused at a breakpoint with active call frame. Returns: expression result with type and value. Use this to inspect variables and call stack during debugging. Alternatives: 'evaluate_js' for global scope evaluation, 'step_over' to advance without evaluation.
| Name | Required | Description | Default |
|---|---|---|---|
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| expression | Yes | JavaScript expression to evaluate in call frame scope. Constraints: valid JavaScript accessing local/closure variables. Interactions: requires active paused debugger session; has access to function parameters and local variables. Defaults to: None (required). | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden and handles it well: it discloses side effects ('read-only by default; can modify state if expression includes mutations') and prerequisites. It could go further (e.g., error behavior, impact on debugger state) but is transparent about the key behavioral traits.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is efficiently structured: purpose, side effects, prerequisites, return info, and alternatives are each covered in one sentence without repetition. Though slightly long, every sentence adds value and the key information is front-loaded.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's moderate complexity, the description covers purpose, side effects, prerequisites, return type, and alternatives. Without an output schema, it explains what the result contains ('type and value'). It doesn't elaborate on error messages or handling, but the essential information for correct invocation is present.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so parameters are well-documented. The description adds semantic context that the schema lacks, such as 'in call frame scope' and access to local/closure variables, clarifying what the expression can reference and the evaluation context. This goes beyond the baseline.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states a specific verb ('Evaluates') and resource ('JavaScript expressions within the scope of a paused call frame') and distinguishes itself from siblings like 'evaluate_js' and 'step_over'. It also gives a concrete use case ('inspect variables and call stack during debugging'), making its purpose unmistakable.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Explicitly mentions the prerequisite ('requires debugger to be paused at a breakpoint with active call frame') and names alternatives with reasoning ('evaluate_js' for global scope, 'step_over' to advance without evaluation). This provides clear when-to-use and when-not-to-use guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
fill_inputA
Focuses an input field via CSS selector and inserts text using native input simulation, triggering input/change events. Side effects: modifies DOM input value; triggers input/change event handlers. Prerequisites: element must exist, be visible, and be an input/textarea or contenteditable element. Returns: success confirmation. Use this to populate form fields, search boxes, text areas. Alternatives: 'evaluate_js' for direct value assignment without events, 'click_element' to focus manually.
| Name | Required | Description | Default |
|---|---|---|---|
| text | Yes | Text content to insert. Constraints: any string (special chars escaped automatically). Interactions: replaces any existing text after focus; triggers input/change events. Defaults to: None (required). | |
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| selector | Yes | CSS selector identifying the input element. Constraints: valid CSS selector matching an input/textarea/contenteditable element. Interactions: element must be focusable and writable. Defaults to: None (required). | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and meets it. It discloses side effects (modifies DOM value, triggers input/change events), prerequisites (element exists, visible, input/textarea/contenteditable), and return type (success confirmation). This is thorough behavioral disclosure.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is well structured and efficient: opening action, side effects, prerequisites, return, usage, alternatives. Every sentence provides distinct value with no redundancy or fluff.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a 4-parameter tool with no output schema, the description fully covers what the tool does, when to use it, behavioral side effects, prerequisites, and return value. It is complete enough for an agent to select and invoke it correctly without ambiguity.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% and each parameter has a detailed description already. The tool description adds only general context ('CSS selector', 'input/textarea/contenteditable') already present in the schema. Baseline 3 is appropriate since the schema handles parameter semantics.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb ('focuses', 'inserts text') and resource ('input field via CSS selector'), and explains the native input simulation with event triggering. It distinguishes itself from siblings by naming evaluate_js and click_element as alternatives.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Explicitly states when to use: 'Use this to populate form fields, search boxes, text areas.' It also gives clear alternatives and their distinguishing conditions: evaluate_js for direct value assignment without events, click_element to focus manually.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get_console_logsA
Retrieves cached console messages including log, warning, error, info levels and uncaught exceptions. Side effects: when 'clear' is true the cached console messages are emptied after being returned. Prerequisites: requires an active Chrome tab. Returns: JSON array of console messages with timestamp, level, and text. Use this to debug script errors, monitor page health, inspect exception traces. Alternatives: browser DevTools Console, error logging services.
| Name | Required | Description | Default |
|---|---|---|---|
| clear | No | Clear console cache after returning logs. Constraints: boolean. Interactions: when true, subsequent calls only return new messages. Defaults to: false. | |
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. | |
| level_filter | No | Filter logs by severity level (case-insensitive). Constraints: 'error', 'warning', 'info', 'log', or similar CDP log level. Interactions: when provided, returns only matching level; empty returns all. Defaults to: None (no filtering). |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It openly states the side effect of 'clear' (emptying cache after return), the prerequisite, and the return format. It does not mention potential errors or failure modes, but it sufficiently discloses the critical behaviors an agent needs to know. The absence of annotations makes this transparency valuable.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is well-structured and front-loaded with the primary purpose. It flows logically through side effects, prerequisites, returns, usage, and alternatives. Every sentence contributes meaningful information, with no redundancy or fluff. It is concise and scannable.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's moderate complexity (4 params, no output schema), the description covers all essential aspects: what it does, side effects, prerequisites, return format, and use cases. An agent can correctly invoke this tool based solely on the description and schema. There are no obvious gaps that would lead to misuse.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the baseline is 3. The description adds context about the 'clear' side effect, which clarifies its parameter's behavior, but does not elaborate on other parameters (tab_id, instance_id, level_filter) beyond what the schema already states. The added value is marginal, so 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the verb 'Retrieves' and the resource 'cached console messages', list specific log levels and exceptions. It distinguishes itself from sibling tools like get_network_logs by specifying console messages. The usage context ('debug script errors, monitor page health') further clarifies its purpose.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides clear prerequisites ('requires an active Chrome tab') and explicit use cases, but does not explicitly state when not to use it or directly compare to sibling tools. It mentions external alternatives (DevTools Console, error logging services) but excludes no sibling tools, leaving some ambiguity about when to prefer this over get_network_logs or similar. However, the context is still clear.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get_custom_eventsA
EXPERIMENTAL: Retrieves unhandled CDP events from domains not covered by specialized listeners (network, console, etc.). Side effects: none (read-only cache access). Prerequisites: requires active Chrome connection with send_cdp_command or custom domain listeners active. Returns: JSON array of custom events with method, parameters, and timestamp. Use this to see Target, Debugger, or other domain events. Alternatives: domain-specific listeners (get_network_logs, get_console_logs).
| Name | Required | Description | Default |
|---|---|---|---|
| limit | Yes | Maximum number of events to return. Constraints: positive integer (0 = unlimited, clamped to cache size). Interactions: limits result set size. Defaults to: 100. | |
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. | |
| filter_method | No | Filter events by CDP method name (case-sensitive). Constraints: string matching format 'Domain.eventName'. Interactions: when omitted, returns all events. Defaults to: None (no filtering). |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description correctly bears the full burden. It discloses 'Side effects: none (read-only cache access)', notes the 'EXPERIMENTAL' status, and explains the return format. It could additionally mention behavior on empty results or error conditions, but for a read-only cache tool, the provided transparency is comprehensive.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is compact, front-loaded with the experimental warning and core purpose, then covers side effects, prerequisites, return format, use cases, and alternatives. Every sentence adds value without redundancy.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Despite having no output schema and no annotations, the description covers purpose, usage, side effects, prerequisites, return structure, and alternatives. For a read-only tool with clear schema documentation, this is complete enough for an agent to decide when and how to use it correctly.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema describes all parameters with constraints, defaults, and interactions (100% coverage). The description adds no additional parameter-specific semantics beyond the schema, so the baseline of 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states 'Retrieves unhandled CDP events from domains not covered by specialized listeners', specifying the verb, resource, and scope. It explicitly contrasts with siblings like get_network_logs and get_console_logs, making the tool's purpose unambiguous and distinct.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It provides explicit usage guidance: 'Use this to see Target, Debugger, or other domain events' and names alternatives, including specific sibling tools. It also mentions prerequisites (active Chrome connection with send_cdp_command or custom domain listeners), giving clear conditions for when to use the tool.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get_network_logsA
Retrieves intercepted HTTP/REST requests and WebSocket frames from network activity cache with filtering. Side effects: when 'clear' is true the cached requests and WebSocket frames are emptied after being returned. Prerequisites: requires active Chrome tab with network monitoring enabled. Returns: JSON array of requests/WebSocket frames with optional full details ('include_details' defaults to true; set false for summary only). Parameters: 'current_navigation_only' limits results to current navigation only (defaults to false, retaining up to 3 navigations). Rate limits: none. Use this to audit API calls, debug network issues, inspect WebSocket traffic. Alternatives: browser DevTools Network tab, HAR file export.
| Name | Required | Description | Default |
|---|---|---|---|
| clear | No | Clear network cache after returning logs. Constraints: boolean. Interactions: when true, subsequent calls return only new traffic. Defaults to: false. | |
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| url_filter | No | Partial URL match (case-insensitive). Constraints: non-empty string. Interactions: filters both REST and WebSocket URLs; empty string disables filtering. Defaults to: None (no URL filtering). | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. | |
| type_filter | No | Traffic type to include. Constraints: 'rest', 'websocket', or 'both' (case-insensitive). Interactions: limits results to specified type. Defaults to: "both". | |
| include_details | No | Include full request/response details. Constraints: boolean. Interactions: when false, returns summary only (URL, method, status); when true, includes headers, bodies. Defaults to: true. | |
| ws_content_filter | No | WebSocket payload substring match (case-insensitive). Constraints: non-empty string. Interactions: applies only when type_filter includes 'websocket'; filters by payload content. Defaults to: None (no content filtering). | |
| ws_direction_filter | No | WebSocket frame direction filter. Constraints: 'sent', 'received', or 'both'. Interactions: applies only when type_filter includes 'websocket'. Defaults to: "both". | |
| current_navigation_only | No | Limit results to current navigation only. Constraints: boolean. Interactions: when false, includes up to 3 retained navigations. Defaults to: false. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It discloses the destructive side effect of 'clear' (empties cache), prerequisites ('requires active Chrome tab with network monitoring enabled'), rate limits ('none'), and return format. This exceeds typical transparency and directly addresses potential risks and operational constraints.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is well-structured with a clear progression: purpose, side effects, prerequisites, return info, parameter highlights, rate limits, usage, and alternatives. It is somewhat lengthy but every sentence adds value; no fluff. Front-loading the main purpose aids quick comprehension.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool with 9 parameters, no output schema, and no annotations, the description covers side effects, prerequisites, return type, usage, and alternatives. It does not detail the exact JSON structure of the returned array, but given the include_details flag and the schema's description of fields, it is reasonably complete. A slight gap is the lack of error conditions or behavior when prerequisites are unmet.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so all nine parameters are already described in detail. The description reiterates some parameter behaviors (e.g., current_navigation_only default and retention, include_details default) but adds no new information beyond the schema. Thus baseline 3 applies.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
Description opens with a specific verb-resource pair: 'Retrieves intercepted HTTP/REST requests and WebSocket frames from network activity cache with filtering.' This clearly distinguishes it from sibling tools like get_console_logs or get_performance_metrics. It also mentions the cache context and filtering, making the purpose unambiguous.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Explicit usage scenarios are given: 'Use this to audit API calls, debug network issues, inspect WebSocket traffic.' Alternatives are named (DevTools Network tab, HAR export), though they are external rather than sibling tools. It does not explicitly state when not to use it vs other tools, but the scenarios and alternatives provide adequate guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get_performance_metricsA
Captures runtime performance metrics including JS heap size, DOM node count, and layout timing. Side effects: none (read-only snapshot). Prerequisites: requires an active Chrome tab. Returns: JSON object mapping metric names to numeric values (e.g., JSHeapUsedSize, LayoutCount). Use this to monitor memory usage, detect memory leaks, or profile performance. Alternatives: 'profile_page_performance' for detailed tracing, browser DevTools Performance tab.
| Name | Required | Description | Default |
|---|---|---|---|
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description discloses key behavioral traits: it explicitly notes 'Side effects: none (read-only snapshot)' and 'Prerequisites: requires an active Chrome tab'. It also specifies the return format. This is strong coverage, though it doesn't mention what happens if no active tab exists or whether there are rate limits, which are minor gaps.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is structured logically: purpose, side effects, prerequisites, returns, usage, alternatives. Each sentence adds value and information is front-loaded. It is slightly longer than necessary but remains efficient and scannable.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's simplicity (2 optional parameters, read-only, returns JSON), the description is fully complete: it explains the return structure with examples, includes side-effects and prerequisites, and gives usage guidance. An agent can call this tool correctly without any further information.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the schema already fully documents both parameters (tab_id and instance_id). The description adds no additional nuance beyond the schema's existing explanations. With full schema coverage, the baseline of 3 is appropriate; the description does not need to compensate much.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool captures runtime performance metrics (JS heap size, DOM node count, layout timing) and explicitly distinguishes it from 'profile_page_performance' which does detailed tracing. It identifies both the verb and resource precisely, making it unambiguous among siblings.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It explicitly states when to use the tool ('monitor memory usage, detect memory leaks, or profile performance') and names the alternative ('profile_page_performance' for detailed tracing, plus browser DevTools Performance tab). This provides a clear decision pathway without needing to inspect other tool definitions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
inspect_domA
Retrieves the complete HTML document or a contextual snippet around a search query. Side effects: none (read-only). Prerequisites: requires an active Chrome tab with loaded DOM. Returns: full HTML or snippet with context markers. Use this to inspect page structure, find elements by text, or verify rendering. Alternatives: 'evaluate_js' for complex DOM queries, 'capture_screenshot' for visual verification.
| Name | Required | Description | Default |
|---|---|---|---|
| after | No | Characters to include after the match. Constraints: non-negative integer. Interactions: only applies if 'query' provided. Defaults to: 200. | |
| query | No | Text pattern to search for in the DOM (case-sensitive). Constraints: any string. Interactions: when provided, returns context snippet instead of full HTML. Defaults to: None (returns full HTML if omitted). | |
| before | No | Characters to include before the match. Constraints: non-negative integer. Interactions: only applies if 'query' provided. Defaults to: 200. | |
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It explicitly states side effects are none (read-only), prerequisites require an active Chrome tab with loaded DOM, and describes the return format as full HTML or snippet with context markers. This is strong coverage. It stops short of 5 because it omits potential failure cases (e.g., no match, invalid tab) or rate limits, but for a read-only inspection tool this is nearly complete.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is three sentences with no extra fluff. The main purpose is front-loaded, followed by side effects, prerequisites, returns, usage, and alternatives. Every sentence earns its place, and the structure is logical and scannable.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool with 5 parameters, no output schema, and no annotations, this description covers the essential context: purpose, usage, safety (read-only), prerequisites, and return behavior. The mention of context markers gives a clue about the snippet format. It could be more explicit about error handling or edge cases (e.g., no match for query), but overall it is sufficiently complete for an agent to invoke it correctly.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the schema already documents each parameter. The description adds value by clarifying the two operational modes: full HTML when query is omitted, and contextual snippet with markers when query is provided. This maps directly to the query, before, and after parameters and gives the agent a higher-level understanding. It does not duplicate parameter details but adds conceptual grouping.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool retrieves the complete HTML document or a contextual snippet around a search query. It specifies the exact action (retrieves) and resource (HTML/snippet), and explicitly differentiates from alternatives by naming them (evaluate_js, capture_screenshot). This leaves no ambiguity about what inspect_dom does.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives explicit use cases: inspect page structure, find elements by text, verify rendering. It also names specific alternatives and the conditions that select them (complex DOM queries → evaluate_js, visual verification → capture_screenshot), providing clear when-to-use and when-not-to-use guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
list_instancesA
Lists all running or registered Chrome instances. Side effects: none (read-only registry snapshot). Returns: JSON array of instance descriptors with id, label, host, port, profile_dir, features and is_default. Use this to discover instance_ids before passing 'instance_id' to other tools. Alternatives: 'list_tabs' to enumerate tabs within an instance.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries full burden. It discloses 'Side effects: none (read-only registry snapshot)' and specifies the return format as a JSON array with field names. This is transparent about behavior and output, exceeding the minimum for a tool without annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two sentences with no wasted words. The purpose is front-loaded, followed by side effects, return format, usage guidance, and an alternative. Every sentence adds value.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple list tool with no parameters and no output schema, the description is complete: it covers purpose, side effects, return format, and how to use it with other tools. An agent can confidently invoke this tool.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Tool has zero parameters, so schema coverage is 100% (trivially). Baseline for 0 params is 4. The description doesn't discuss parameters, but none exist; it compensates by explaining output fields, which is outside parameter semantics.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool lists all running or registered Chrome instances, with a specific verb and resource. It also names an alternative (list_tabs) to differentiate scope, so an agent can distinguish it without opening schemas.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Explicitly states when to use this tool ('discover instance_ids before passing instance_id to other tools') and names list_tabs as an alternative for a different scope. Provides clear usage context and exclusion.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
list_tabsA
Lists all tabs currently open and registered in the specified Chrome instance. Side effects: none (read-only registry snapshot). Returns: structured JSON with 'active_tab_id', the current tab targeted by tools that omit 'tab_id', and a 'tabs' array of tab_id, label, target_id and url. When no tabs are registered, tools fall back to the instance's default single-tab connection and a 'note' explains it. Use this to discover Tab IDs before passing 'tab_id' to other tools. Alternatives: 'list_instances' to enumerate Chrome instances.
| Name | Required | Description | Default |
|---|---|---|---|
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description explicitly discloses side effects ('none (read-only registry snapshot)') and describes the fallback behavior when no tabs are registered, including the note in the response. With no annotations provided, this fully carries the behavioral transparency burden and exceeds it by explaining return structure and special cases.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is structured with distinct sections (purpose, side effects, returns, fallback, usage, alternative) and front-loads the core purpose. It is slightly verbose but every sentence adds unique, relevant information, so no waste.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple read-only tool with one optional parameter and no output schema, the description covers return format (active_tab_id, tabs array, note), side effects, fallback behavior, usage guidance, and alternatives. Nothing an agent needs to call it correctly is missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The single parameter (instance_id) is already fully described in the schema (100% coverage), and the description adds no additional semantics beyond the schema's mention of omitting it for the default instance. It does tie the parameter to discovering Tab IDs, but that's purpose rather than parameter meaning, so a baseline 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific verb ('Lists'), resource ('all tabs'), and scope ('in the specified Chrome instance'), and explicitly distinguishes itself by noting it returns Tab IDs for use with other tools, making it unambiguous against siblings like list_instances and open_tab.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It clearly states when to use the tool ('to discover Tab IDs before passing tab_id to other tools') and provides an explicit alternative ('list_instances' for enumerating instances), enabling proper routing without inference.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
open_instanceA
Opens a new independent Chrome instance. Side effects: launches a separate Chrome process with its own profile directory and remote-debugging port. Prerequisites: rejected when the server runs in --user-profile mode (Chrome's singleton profile lock). Returns: structured JSON with 'instance_id' (pass it as the 'instance_id' argument of other tools), 'host', 'port' and 'profile_dir'. Use this to isolate browsing sessions, cookies, proxies or WebMCP contexts from one another. Alternatives: 'open_tab' for additional tabs within an existing instance. Parameters: 'features' accepts a closed set - 'WEBGL_SOFTWARE' (forces SwiftShader software WebGL for GPU-less environments); 'headless' defaults to false (prefer false so the user can see the browser).
| Name | Required | Description | Default |
|---|---|---|---|
| label | No | Optional label to identify the instance. The label becomes the instance_id returned by this tool and accepted by the 'instance_id' argument of other tools. If omitted, a dynamic label is generated. | |
| proxy | No | Optional proxy server configuration. | |
| features | No | Optional feature presets (e.g. WEBGL_SOFTWARE). | |
| headless | No | Optional headless mode. Encouraged to be set to false so that the user can see what happens with the browser. Defaults to false. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does so well: it discloses side effects (separate Chrome process, own profile directory and remote-debugging port), a prerequisite failure mode (rejected under --user-profile due to Chrome's singleton lock), and the return shape.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Purpose is front-loaded, then side effects, prerequisites, returns, usage, and alternatives in a logical order. It is dense but nearly every clause carries information; minor compression is possible in the parameter section.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Covers purpose, when-to-use, alternatives, side effects, prerequisites, and return values with no output schema present. Everything an agent needs to decide and call correctly is present.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the baseline is 3, but the description adds meaning beyond the schema: it explains what WEBGL_SOFTWARE does (forces SwiftShader for GPU-less environments) and the default/rationale for headless. Proxy and label mapping to instance_id are largely covered by the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb and resource ('Opens a new independent Chrome instance') and distinguishes it from the sibling 'open_tab', which creates tabs within an existing instance. The 'independent' qualifier sets the scope precisely.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Explicitly states when to use it ('to isolate browsing sessions, cookies, proxies or WebMCP contexts') and names the alternative ('open_tab' for additional tabs within an existing instance). It also states a prerequisite rejection condition (--user-profile mode).
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
open_tabA
Opens a new tab in the specified Chrome instance. Side effects: creates a browser tab and registers it under a generated Tab ID; the tab stays open until closed with 'close_tab'. Prerequisites: none - the instance is launched lazily if not running yet. Returns: structured JSON with 'tab_id' (use it as the 'tab_id' argument of other tools), 'target_id' (raw CDP target id), 'url' and 'label'. Use this to work with several pages in parallel while keeping their CDP state isolated per tab. Alternatives: 'navigate' to load content in the active tab, 'list_tabs' to enumerate already open tabs.
| Name | Required | Description | Default |
|---|---|---|---|
| url | No | Target URL to navigate to in the new tab. Defaults to 'about:blank'. | |
| label | No | Optional unique label to identify the tab. Rejected if another tab in this instance already uses it. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Since no annotations are provided, the description fully discloses behavior: it mentions side effects (creates a tab, registers ID, stays open until close_tab), lazy instance launch, and the exact return structure (tab_id, target_id, url, label). This goes beyond the schema and gives the agent a complete mental model.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is well-structured, front-loading the purpose and then detailing side effects, return values, usage, and alternatives. It is slightly verbose but every sentence contributes meaningful information without redundancy, earning a solid 4.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's complexity (3 optional params, no output schema, 30+ siblings), the description is complete: it covers what, why, when, side effects, return format, and differentiation from related tools. An agent has everything needed to call it correctly.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema already covers all parameters at 100%, but the description adds value: url defaults to 'about:blank', label must be unique, and instance_id derives from open_instance/list_instances with an 'omit for default' guidance. This enriches the agent's understanding beyond raw schema types.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool's function: 'Opens a new tab in the specified Chrome instance.' It names the specific resource (tab) and the action (open), and differentiates itself from siblings by explicitly mentioning 'navigate' and 'list_tabs' as alternatives with different purposes.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description explicitly states when to use this tool: 'Use this to work with several pages in parallel while keeping their CDP state isolated per tab.' It also provides clear alternatives: 'navigate' for altering the active tab and 'list_tabs' for enumerating existing tabs, giving an agent precise routing guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
pause_on_loadA
Enables the debugger and injects a breakpoint at the first statement of any script loaded after reloading the page. Side effects: reloads the current page (destructive of unsaved state). Prerequisites: requires an active Chrome tab. Returns: confirmation of debugger enablement and page reload. Use this to debug script execution from the page load. Alternatives: 'set_breakpoint' for targeting specific scripts/lines, 'pause_on_exceptions' for exception-based pausing.
| Name | Required | Description | Default |
|---|---|---|---|
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It explicitly discloses the destructive side effect ('reloads the current page (destructive of unsaved state)'), prerequisites, and the return value. This is more than sufficient for an agent to understand the tool's behavior and risks.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is well-organized into distinct clauses: purpose, side effects, prerequisites, return, usage, and alternatives. Every sentence provides essential information without redundancy, and the primary purpose is front-loaded. It is efficient despite covering multiple aspects.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given there is no output schema, the description compensates by stating the return value ('confirmation of debugger enablement and page reload'). It covers prerequisites, side effects, usage, and alternatives, leaving no critical operational detail missing. For a tool with only optional parameters and clear behavior, this is complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, meaning both parameters (tab_id and instance_id) are already fully described in the schema. The description adds no additional parameter-specific meaning, so it meets the baseline expectation but does not exceed it.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the specific action: 'Enables the debugger and injects a breakpoint at the first statement of any script loaded after reloading the page.' It also distinguishes itself from siblings by explicitly naming alternatives, so an agent can immediately tell it apart from set_breakpoint and pause_on_exceptions.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It explicitly states when to use the tool ('Use this to debug script execution from the page load.') and provides alternative tools with their different purposes ('set_breakpoint' for targeting specific scripts/lines, 'pause_on_exceptions' for exception-based pausing). It also mentions the prerequisite of an active Chrome tab, giving complete usage context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
profile_page_performanceA
Records a performance trace of page execution, calculating Core Web Vitals (FCP, LCP, DCL, Load) and identifying Long Tasks (>50ms blocking). Side effects: may temporarily disable cache ('disable_cache' defaults to false); impacts page memory/CPU. Prerequisites: requires an active Chrome tab; trace recording uses background bandwidth. Returns: JSON with vitals, blocking time, and top 5 long tasks. Use this to optimize performance, identify bottlenecks, measure cold starts. Alternatives: browser DevTools Performance tab, real user monitoring (RUM).
| Name | Required | Description | Default |
|---|---|---|---|
| action | No | Action to trigger during tracing. Constraints: 'none' or 'reload'. Interactions: 'reload' restarts page recording from initial load (useful with disable_cache=true). Defaults to: "none". | |
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| duration_ms | No | Recording duration in milliseconds. Constraints: integer between 500 and 15000. Interactions: longer duration captures more data; use 3000-5000 for typical pages. Defaults to: 3000. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. | |
| disable_cache | No | Disable network cache during trace. Constraints: boolean. Interactions: when true with action='reload', simulates cold start; cache restored after profiling. Defaults to: false. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries full responsibility for behavioral disclosure, and it does so thoroughly. It states side effects: 'may temporarily disable cache ('disable_cache' defaults to false); impacts page memory/CPU.' It also mentions prerequisites: 'requires an active Chrome tab' and background bandwidth usage. It discloses the return format: 'JSON with vitals, blocking time, and top 5 long tasks.' This is comprehensive for a tool with no annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is compact and well-structured. It front-loads the primary purpose, then efficiently covers side effects, prerequisites, return format, usage scenarios, and alternatives in a few sentences. Every clause contributes meaningful information—no filler or redundancy.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Despite having 5 parameters and no output schema, the description covers everything an agent needs to call the tool correctly: what it does, when to use it, side effects, prerequisites, return structure, and parameter interactions. The parameter details are in the schema, so the description compensates well for the lack of an output schema by specifying the JSON contents.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the schema already documents each parameter. However, the description adds meaningful interaction context beyond the schema: e.g., 'when true with action='reload', simulates cold start; cache restored after profiling' for disable_cache, and 'use 3000-5000 for typical pages' for duration_ms. This adds value beyond the schema's basic descriptions.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool's purpose: 'Records a performance trace of page execution, calculating Core Web Vitals (FCP, LCP, DCL, Load) and identifying Long Tasks (>50ms blocking).' It specifies a concrete action (records), resource (performance trace), and the specific metrics, which distinguishes it from sibling tools like get_performance_metrics that likely fetch existing metrics rather than record a fresh trace.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives explicit usage context: 'Use this to optimize performance, identify bottlenecks, measure cold starts.' It also names alternatives: 'Alternatives: browser DevTools Performance tab, real user monitoring (RUM).' This tells the agent when to use it and what other approaches exist, though it doesn't explicitly state when NOT to use it, which is a minor gap.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
reloadA
Reloads the current page, discarding all unsaved changes and re-fetching resources from the server. Side effects: destructive of unsaved state; clears dynamic DOM state. Prerequisites: requires an active Chrome tab. Returns: reload confirmation. Use this to refresh page content or reset to initial load state. Alternatives: 'navigate' to load a different URL, 'pause_on_load' to debug reload execution.
| Name | Required | Description | Default |
|---|---|---|---|
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It explicitly mentions destructive side effects (discards unsaved changes, clears dynamic DOM), prerequisites (active Chrome tab), and the return value (reload confirmation). This is thorough and leaves nothing hidden.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is front-loaded with the main action, then covers side effects, prerequisites, return, usage, and alternatives in a logical order. Each sentence adds unique value without redundancy, and the total length is appropriate for the information conveyed.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool with two optional parameters and no output schema, the description covers everything an agent needs: what it does, side effects, prerequisites, return type, usage scenarios, and alternatives. Nothing essential is missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema provides full descriptions for both parameters (tab_id and instance_id) with 100% coverage, so the description doesn't need to add more. The baseline of 3 is appropriate because the description adds no parameter-specific information beyond what the schema already explains, but the schema fully documents them.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific verb (reload) and resource (current page), and adds context by noting it discards unsaved changes and re-fetches resources. It explicitly distinguishes itself from siblings by naming navigate (for different URL) and pause_on_load (for debugging reload), so an agent can clearly tell it apart.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives explicit when-to-use guidance: 'Use this to refresh page content or reset to initial load state.' It also names alternatives with conditions ('navigate' to load a different URL, 'pause_on_load' to debug reload execution) and states a prerequisite (requires an active Chrome tab). This is complete usage guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
remove_breakpointA
Removes a previously set debugger breakpoint by its ID, allowing execution to pass that location uninterrupted. Side effects: modifies debugger state (breakpoint deleted). Prerequisites: requires an active, paused debugger session with the breakpoint ID returned from 'set_breakpoint'. Returns: confirmation of breakpoint removal. Use this to clean up breakpoints or disable debugging at specific locations. Alternatives: 'set_breakpoint' to add new breakpoints, 'resume' to continue execution.
| Name | Required | Description | Default |
|---|---|---|---|
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. | |
| breakpoint_id | Yes | Unique identifier of the breakpoint (returned from set_breakpoint). Constraints: non-empty string matching format from set_breakpoint response. Interactions: must correspond to an active breakpoint or operation will fail. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Since no annotations are provided, the description carries the full burden of behavioral disclosure. It clearly states side effects (modifies debugger state, breakpoint deleted), prerequisites, and return value (confirmation of removal). It does not detail error cases beyond the schema's note on failure, but for this tool that is sufficient.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is concise but comprehensive, front-loading the action and then covering side effects, prerequisites, return, usage, and alternatives in a logical order. No fluff, every sentence adds value. Slightly verbose for a simple tool, but well-structured.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's simplicity, the absence of an output schema, and the full coverage of parameters by the schema, the description covers all necessary context: what it does, when to use it, side effects, prerequisites, and return. It does not mention potential errors beyond the schema's note, but that's not critical for this operation.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the schema already documents all parameters, including breakpoint_id ('Unique identifier of the breakpoint', constraints, interactions). The description does not add additional parameter-specific meaning beyond reinforcing that breakpoint_id comes from set_breakpoint, which is already in the schema. Baseline 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the specific verb 'Removes' and the resource 'breakpoint' by its ID. It distinguishes itself from siblings by explicitly naming set_breakpoint and resume as alternatives, making it unambiguous which tool to pick.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It provides explicit when-to-use guidance ('Use this to clean up breakpoints or disable debugging at specific locations') and names concrete alternatives with their purposes. The prerequisites to call it are also stated (active, paused session with breakpoint ID from set_breakpoint).
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
restart_chromeA
Stops and restarts the Chrome instance selected by 'instance_id' (the default instance when omitted) with remote debugging enabled, optionally configuring proxy and opt-in capability presets. Side effects: destructive - terminates that instance's Chrome process and all its open tabs; closes its debugging connection; other instances keep running. Prerequisites: requires CHROME_PATH environment variable or chrome in PATH. Returns: restart success confirmation listing the presets applied. Use this to reset browser state, apply proxy settings, enable experimental browser capabilities, recover from crashes. Alternatives: 'reload' to refresh page without restart, 'navigate' to load new content. Parameters: 'features' accepts a closed set - 'WEBGL_SOFTWARE' (forces SwiftShader software WebGL for GPU-less environments); arbitrary Chrome flags are not accepted.
| Name | Required | Description | Default |
|---|---|---|---|
| features | No | Chrome capability presets to enable on the new instance. Constraints: closed set - 'WEBGL_SOFTWARE' forces SwiftShader software WebGL for GPU-less environments. Arbitrary Chrome flags are not accepted. Interactions: presets apply only to the instance started by this call and are cleared by a later restart that omits them. Defaults to: [] (no presets). | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. | |
| proxy_server | No | Proxy server URL (e.g., 'http://proxy.example.com:8080'). Constraints: valid proxy URL with protocol and port. Interactions: applied to new Chrome instance; requires 'enable_proxy_auth' for authenticated proxies. Defaults to: None (no proxy). |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does so: it declares destructive side effects (terminates the Chrome process and all open tabs, closes the debugging connection, other instances unaffected) plus a prerequisite (CHROME_PATH or chrome in PATH) and the return shape. This is exactly the behavioral context an agent needs before calling a destructive tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Front-loaded with the core action, then labeled sections (Side effects, Prerequisites, Returns, Alternatives, Parameters) that make it scannable. It is long, but almost every sentence carries distinct information; only the parameter restatement overlaps with the schema.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a destructive tool with no annotations and no output schema, the description covers side effects, prerequisites, return value, usage triggers, and alternatives. An agent has everything needed to call it correctly and safely.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% and the schema itself documents all three parameters in depth, including the closed-set constraint on 'features' and the proxy URL format. The description largely restates this (closed feature set, default instance) rather than adding new syntax or interaction detail, so baseline 3 applies.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb and resource ('Stops and restarts the Chrome instance'), names the targeting parameter and the default-instance fallback, and distinguishes itself from siblings by naming 'reload' and 'navigate' as alternatives. An agent can tell exactly what this does without opening the schema.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Explicitly enumerates when to use it ('reset browser state, apply proxy settings, enable experimental browser capabilities, recover from crashes') and when to prefer alternatives ('reload' to refresh, 'navigate' to load new content). Nothing is left to inference.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
resumeA
Continues full execution of the debugger from current breakpoint. Side effects: advances code execution until next breakpoint or completion. Prerequisites: requires an active, paused debugger session. Returns: confirmation of resume command. Use this to continue program flow after inspection. Alternatives: 'step_over' or 'step_out' for single-step execution.
| Name | Required | Description | Default |
|---|---|---|---|
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden of behavioral disclosure. It states side effects ('advances code execution until next breakpoint or completion'), prerequisites, and the return confirmation. It does not mention whether the operation is reversible or if it alters breakpoints, but the core behavioral impact (execution resumes) is clearly disclosed. This is more than adequate for the tool's purpose.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is concise and well-structured. Each sentence delivers distinct value: the action, side effects, prerequisites, return, usage guidance, and alternatives are all clearly separated. It front-loads the core function and keeps the description to four sentences without redundancy.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool that simply resumes a debugger, the description covers all essential aspects: what it does, conditions for use, what to expect as a result, and alternatives. There is no output schema, but the description's return statement ('confirmation of resume command') suffices. An agent has everything needed to call this tool correctly.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema provides 100% coverage for both parameters (tab_id and instance_id) with clear descriptions. The tool description does not add new parameter semantics, but none are needed since the schema already explains them. Baseline of 3 is appropriate here.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool's function: 'Continues full execution of the debugger from current breakpoint.' It uses a specific verb ('continues') and resource ('full execution of the debugger'), and explicitly distinguishes itself from single-step alternatives, making it easy for an agent to differentiate from siblings like step_over.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description explicitly says when to use it ('Use this to continue program flow after inspection') and names alternatives ('step_over' or 'step_out' for single-step execution). It also states the prerequisite: 'requires an active, paused debugger session.' This leaves no ambiguity about when to select this tool over others.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
scrollA
Scrolls the page by pixel offset, viewport pages, or to a specific element using CSS selector. Side effects: modifies DOM scroll position (observable but reversible). Prerequisites: requires an active Chrome tab with content. Returns: scroll completion confirmation. Use this to navigate within long pages or bring elements into view. Alternatives: 'click_element' to trigger scroll by clicking, 'evaluate_js' for custom scroll logic.
| Name | Required | Description | Default |
|---|---|---|---|
| x | No | Horizontal scroll distance in pixels. Constraints: integer (positive=right, negative=left). Interactions: ignored if 'selector' is provided; combined with 'y' for diagonal scrolling. Defaults to: 0 (no horizontal scroll). | |
| y | No | Vertical scroll distance in pixels. Constraints: integer (positive=down, negative=up). Interactions: ignored if 'selector' or 'pages' is provided; overridden by 'pages'. Defaults to: 0 (no vertical scroll). | |
| pages | No | Number of viewport heights to scroll vertically. Constraints: positive float (e.g., 1.5 = 1.5× viewport height). Interactions: takes precedence over 'y' parameter if both provided; ignored if 'selector' provided. Defaults to: None. | |
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| selector | No | CSS selector of element to scroll into view. Constraints: valid CSS selector string. Interactions: takes precedence over 'x', 'y', 'pages' if provided; fails if element not found. Defaults to: None. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden and discloses a side effect ('modifies DOM scroll position (observable but reversible)'), a prerequisite, and a return value. This is useful transparency, though it does not go into edge cases like element-not-found failure or lazy-loading behavior.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Four concise sentences front-load the primary action, then cover side effects, prerequisites, return value, use case, and alternatives with no wasted words. Every sentence earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a six-parameter tool with no output schema or annotations, the description gives enough context to use it correctly: purpose, modes, side effects, return confirmation, and relevant alternatives. It could add more about failure modes, but the schema covers parameter-level behavior comprehensively.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The parameter schema already provides 100% coverage with detailed descriptions for each parameter, so the baseline is 3. The description adds a useful high-level mapping of pixel offset, pages, and selector to the underlying parameters, but does not add meaning beyond what the schema already documents.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states a specific verb and resource ('Scrolls the page') and enumerates the three distinct modes: pixel offset, viewport pages, and element selector. It also distinguishes itself from sibling tools by naming click_element and evaluate_js as alternatives.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description explicitly says when to use this tool ('navigate within long pages or bring elements into view') and names alternatives with their purpose ('click_element' for click-triggered scroll, 'evaluate_js' for custom scroll logic). It also provides a prerequisite: requires an active Chrome tab with content.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
search_scriptsA
Searches all cached script sources for a text pattern and returns matching locations (line and column numbers). Side effects: none (read-only query). Prerequisites: scripts must have been parsed and cached by the debugger. Returns: JSON array of matches with script ID, line/column numbers, and line preview. Use this to locate code before setting breakpoints. Alternatives: 'set_breakpoint' for direct breakpoint placement, 'evaluate_js' for runtime code discovery.
| Name | Required | Description | Default |
|---|---|---|---|
| query | Yes | Text pattern or special command to search for. Constraints: non-empty string (empty string returns cached script count). Interactions: '@source' returns first 1000 chars of each script; 'debug' returns script lengths and errors. Defaults to: None (required). | |
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It explicitly states 'Side effects: none (read-only query)' and discloses prerequisites and return format. While it doesn't cover auth or rate limits, for a read-only search tool these are less critical; the description covers the key behavioral traits sufficiently.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is well-structured with clear sections (action, side effects, prerequisites, return, usage, alternatives). Each sentence adds value with no redundancy. It front-loads the primary action and logically groups related information, making it easy for an agent to parse.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description covers all essential context for an agent to correctly invoke the tool: what it does, prerequisites, side effects, return format, and alternatives. Since there is no output schema, the return format explanation is critical and provided. Nothing an agent needs to call it correctly is missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the schema already documents all three parameters in detail. The description does not add extra parameter-level semantics beyond what the schema provides; it focuses on usage context, which is not part of parameter semantics. Baseline of 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the verb ('searches'), the resource ('all cached script sources'), and the result ('matching locations with line and column numbers'). It also distinguishes itself from siblings by naming alternatives and placement guidance, leaving no ambiguity about what the tool does.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Provides explicit when-to-use guidance ('Use this to locate code before setting breakpoints'), clearly states prerequisites ('scripts must have been parsed and cached'), and names two specific alternatives with conditions for selecting them. This fully routes the agent to the correct tool selection.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
send_cdp_commandA
EXPERIMENTAL: Sends raw Chrome DevTools Protocol (CDP) commands to the browser for advanced use cases not covered by specialized tools. Side effects: depends on command; may modify page state, DOM, or trigger navigation. Auth requirements: subject to local-only restrictions if enabled (Page.navigate checked). Prerequisites: requires knowledge of CDP protocol; active Chrome connection. Returns: raw CDP command response as JSON. Use this only when specialized tools inadequate. Alternatives: use domain-specific tools (navigate, click_element, evaluate_js).
| Name | Required | Description | Default |
|---|---|---|---|
| method | Yes | CDP protocol method name (e.g., 'DOM.getDocument', 'Runtime.evaluate'). Constraints: valid CDP domain.method format. Interactions: method must be recognized by Chrome protocol version. | |
| params | No | JSON-formatted parameters for the CDP command. Constraints: valid JSON object string. Interactions: Page.navigate URLs subject to local-only restrictions; empty string or '{}' for no parameters. Defaults to: None. | |
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description fully discloses behavioral traits: side effects ('may modify page state, DOM, or trigger navigation'), auth restrictions (local-only for Page.navigate), and the experimental nature. It clearly states the raw return format. This is exactly what a high-risk tool needs.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is dense but every sentence earns its place: experimental warning, purpose, side effects, auth, prerequisites, return type, and usage guidance. Front-loaded with the 'EXPERIMENTAL' warning and purpose. No filler or repetition.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's complexity (raw CDP, safety, auth, prerequisites) and lack of output schema, the description covers all necessary context: what it does, when to avoid it, side effects, auth, prerequisites, and return format. Nothing an agent needs to safely and correctly invoke it is missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% for all 4 parameters, so the baseline is 3. The description reinforces constraints (e.g., 'Page.navigate URLs subject to local-only restrictions') but does not add meaning beyond what the schema already provides. It mentions the JSON format for params, but the schema says the same. No extra semantic value.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the verb 'sends' with the resource 'raw Chrome DevTools Protocol (CDP) commands' and explicitly frames it as 'for advanced use cases not covered by specialized tools.' It distinguishes itself from siblings by naming alternatives (navigate, click_element, evaluate_js) and stating when it should not be used.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Provides explicit guidance: 'Use this only when specialized tools inadequate' and directly lists alternative tools. It also states prerequisites (knowledge of CDP protocol, active Chrome connection) and auth caveats (local-only restrictions for Page.navigate). This is comprehensive routing advice.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
set_breakpointA
Sets a debugger breakpoint at a specific location, pausing execution when reached. Side effects: modifies debugger state (breakpoint added until removed). Prerequisites: requires an active Chrome tab; target script must be loaded. Returns: breakpoint identifier and location confirmation. Use this to debug specific code paths. Alternatives: 'pause_on_load' for early script execution, 'search_scripts' to find scripts by pattern.
| Name | Required | Description | Default |
|---|---|---|---|
| url | No | Script URL to match. Constraints: one of 'script_hash', 'script_id', or 'url' must be provided. Interactions: mutually exclusive with 'script_hash' and 'script_id'. Defaults to: None. | |
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| script_id | No | Script ID (from Debugger.scriptParsed event). Constraints: one of 'script_hash', 'script_id', or 'url' must be provided. Interactions: mutually exclusive with 'script_hash' and 'url' (first match wins). Defaults to: None. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. | |
| line_number | Yes | Line number where breakpoint is set (0-indexed). Constraints: non-negative integer, must be within script bounds. Interactions: required parameter; combined with 'column_number' to pinpoint exact location. | |
| script_hash | No | Script hash to identify the target script. Constraints: one of 'script_hash', 'script_id', or 'url' must be provided. Defaults to: None. | |
| column_number | No | Column number within the line. Constraints: non-negative integer. Interactions: optional; narrower precision if provided. Defaults to: start of line (0). |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It covers side effects ('modifies debugger state (breakpoint added until removed)'), prerequisites, and return value. While it doesn't mention edge cases like duplicate breakpoints or persistence across navigations, the disclosed side effects and prerequisites are substantive and helpful for an agent deciding to call or not.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is compact and well-structured: two core sentences plus an alternatives sentence. It front-loads the purpose, then side effects, prerequisites, return, and usage guidance. No fluff—every sentence earns its place, and the alternatives are efficiently listed.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool with 7 parameters and no output schema or annotations, the description provides the essential context: purpose, side effects, prerequisites, return, and alternatives. It doesn't detail parameter relationships or error states, but the schema handles parameter specifics. The description is sufficiently complete for an agent to decide on invocation, though a note on persistence or failure handling would push it to 5.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100% per context signals, so the baseline is 3. The description does not add any parameter-specific details beyond the schema; it only mentions the return value, not the parameters themselves. Since the schema already thoroughly explains each parameter with constraints and interactions, the description adds no extra semantic value for parameters, hence a 3.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description opens with a clear verb and resource: 'Sets a debugger breakpoint at a specific location, pausing execution when reached.' It names the exact action and resource, and distinguishes itself from siblings by explicitly mentioning alternatives like 'pause_on_load' and 'search_scripts', making the tool's purpose unambiguous.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description explicitly states when to use: 'Use this to debug specific code paths,' and provides alternatives with conditions: 'Alternatives: ''pause_on_load'' for early script execution, ''search_scripts'' to find scripts by pattern.' It also states prerequisites (active tab, script loaded), giving clear guidance on when it can and should be used.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
step_overB
Executes the current line of code without entering function calls, pausing at the next line. Side effects: advances debugger execution state. Prerequisites: requires an active, paused debugger session. Returns: confirmation of step execution. Use this to skip function internals during debugging. Alternatives: use 'resume' to continue full execution, 'step_over' enters functions, or 'evaluate_on_call_frame' to inspect state without stepping.
| Name | Required | Description | Default |
|---|---|---|---|
| tab_id | No | The Tab ID of the target tab. Omit to use the active tab. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does disclose side effects ('advances debugger execution state'), prerequisites ('requires an active, paused debugger session'), and return value. However, the internal contradiction in the alternatives line undermines the clarity of the behavioral contract.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is front-loaded and has a logical structure (action, side effects, prerequisites, returns, usage). The alternatives sentence is clunky and contains an error, which makes the text less clean than it could be.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description covers prerequisites, side effects, return type, and use case, which is mostly sufficient for a simple debugging action. But the contradictory alternative guidance leaves unresolved ambiguity about when and how to select this tool versus a step-into operation.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the schema sufficiently documents tab_id and instance_id. The description adds no parameter-specific meaning, but per baseline it does not need to.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The opening sentence clearly states the tool's action: executing the current line without entering function calls and pausing at the next line. However, the later alternatives line says 'step_over enters functions', which introduces confusion and slightly blurs the primary definition.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description explicitly says 'Use this to skip function internals' and names resume and evaluate_on_call_frame as alternatives. But it also lists 'step_over' as an alternative that 'enters functions', which is both not an alternative and contradicts the tool's own behavior, potentially misleading an agent about tool selection.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
stop_chromeA
Gracefully terminates the Chrome instance selected by 'instance_id' (the default instance when omitted) and closes all its debugging connections. Side effects: destructive - kills the Chrome process of that instance only; its open tabs are closed; unsaved data lost; other instances keep running. Prerequisites: the instance must be running. Returns: termination success confirmation. Use this to clean up resources, prevent zombie processes, or end a debugging session. Alternatives: 'restart_chrome' to restart instead of stop, 'close_instance' to also remove a secondary instance from the registry.
| Name | Required | Description | Default |
|---|---|---|---|
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden and does so excellently. It discloses destructive side effects (kills the process, closes tabs, loses unsaved data), scope (only that instance, others keep running), prerequisites (instance must be running), and return value (success confirmation). This is comprehensive and prevents surprises.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is longer than strictly necessary but every sentence carries relevant information: action, side effects, prerequisites, return, use cases, and alternatives. The core action is front-loaded, and the text is well-structured. While verbose, it is not wasteful, earning a 4.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a destructive tool with no output schema, the description covers all essential context: what it does, side effects, scope, prerequisites, return value, when to use, and alternatives. An agent has everything needed to call it correctly and anticipate consequences. Complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% for the single parameter (instance_id), and the description repeats the same information ('selected by instance_id', 'default instance when omitted'). No additional semantic meaning is added beyond the schema, so a baseline of 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific action (gracefully terminates) on a specific resource (Chrome instance identified by instance_id), and clearly distinguishes itself from sibling tools like restart_chrome and close_instance by naming them and their different purposes. The purpose is unambiguous.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Explicitly states when to use ('clean up resources, prevent zombie processes, or end a debugging session') and lists alternatives with conditions ('restart_chrome' to restart, 'close_instance' to also remove from registry). This provides clear routing for the agent.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
switch_tabA
Switches the active default tab to the specified Tab ID. Side effects: the switched tab becomes the default target of all subsequent tool calls in this instance that omit 'tab_id'; when 'activate' is true it is also brought to the foreground in the Chrome window ('activate' defaults to true). Prerequisites: the tab must exist (see 'list_tabs'). Returns: structured JSON with the new 'active_tab_id' and whether the tab was brought to the foreground. Use this before interacting with a different page without repeating 'tab_id' on every call. Alternatives: pass 'tab_id' directly on an individual tool call to address a tab without switching.
| Name | Required | Description | Default |
|---|---|---|---|
| tab_id | Yes | The Tab ID to switch to (e.g. 'tab-1'). | |
| activate | No | If true, brings the tab to the foreground in the browser. Defaults to true. | |
| instance_id | No | Chrome instance id from open_instance/list_instances. Omit for the default instance. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries full disclosure burden. It clearly states side effects (becomes default target, brings to foreground when activate is true), prerequisites (tab must exist, with pointer to list_tabs), and return format (structured JSON with active_tab_id and foreground status). This is thorough and accurate.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Each sentence delivers distinct information: action, side effects, defaults, prerequisites, return value, usage guidance, and alternatives. It is front-loaded with the core action and avoids filler. Though slightly long, every clause earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's complexity (side effects, defaults, prerequisites, return), the description covers everything an agent needs: what it does, why to use it, what changes state, and what to expect in response. No output schema exists, so the return description is essential and provided.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the baseline is 3. The description adds meaningful context beyond the schema: it explains that tab_id becomes the default for subsequent calls, and that activate defaults to true and controls foregrounding. This enhances understanding of each parameter without redundancy.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb ('Switches') and a clear resource ('active default tab to the specified Tab ID'). It also differentiates from sibling tools by explaining that unlike passing tab_id directly, this changes the default target, and names alternatives like list_tabs. No ambiguity.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Explicitly says when to use it: 'before interacting with a different page without repeating tab_id on every call.' Also gives the alternative: 'pass tab_id directly on an individual tool call to address a tab without switching.' Provides both use case and exclusion, which is complete guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
7 tool updates
v1.5.1- Removed
enable_proxy_auth - Changed
open_instance2 fields changed- changed
Input schema / properties / features / descriptionPrevious value: -"Optional feature presets (e.g. WEB_MCP, WEBGL_SOFTWARE)."New value: +"Optional feature presets (e.g. WEBGL_SOFTWARE)." - changed
Input schema / properties / features / items / enumPrevious value: -[ - "WEB_MCP", - "WEBGL_SOFTWARE" -]New value: +[ + "WEBGL_SOFTWARE" +]
- Changed
restart_chrome2 fields changed- changed
Input schema / properties / features / descriptionPrevious value: -"Chrome capability presets to enable on the new instance. Constraints: closed set - 'WEB_MCP' turns on the experimental WebMCP surface for sites that expose tools to the browser; 'WEBGL_SOFTWARE' forces SwiftShader software WebGL for GPU-less environments. Arbitrary Chrome flags are not accepted. Interactions: presets apply only to the instance started by this call and are cleared by a later restart that omits them. Defaults to: [] (no presets)."New value: +"Chrome capability presets to enable on the new instance. Constraints: closed set - 'WEBGL_SOFTWARE' forces SwiftShader software WebGL for GPU-less environments. Arbitrary Chrome flags are not accepted. Interactions: presets apply only to the instance started by this call and are cleared by a later restart that omits them. Defaults to: [] (no presets)." - changed
Input schema / properties / features / items / enumPrevious value: -[ - "WEB_MCP", - "WEBGL_SOFTWARE" -]New value: +[ + "WEBGL_SOFTWARE" +]
- Removed
webmcp_get_invocation - Removed
webmcp_invoke_tool - Removed
webmcp_list_invocations - Removed
webmcp_list_tools
1 tool update
v1.5.0- Changed
get_network_logs1 field changed- added
Input schema / properties / current_navigation_onlyAdded value: +{ + "description": "Limit results to current navigation only. Constraints: boolean. Interactions: when false, includes up to 3 retained navigations. Defaults to: false.", + "type": "boolean" +}
33 tool updates
v1.3.2- Changed
capture_screenshot5 fields changed- removed
Input schema / properties / format / nullableRemoved value: -true - removed
Input schema / properties / full_page / nullableRemoved value: -true - removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / quality / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
click_element2 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
close_tab1 field changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true
- Changed
enable_proxy_auth4 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / prewarm_url / nullableRemoved value: -true - removed
Input schema / properties / resource_type / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
evaluate_js2 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
evaluate_on_call_frame2 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
fill_input2 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
get_console_logs4 fields changed- removed
Input schema / properties / clear / nullableRemoved value: -true - removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / level_filter / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
get_custom_events3 fields changed- removed
Input schema / properties / filter_method / nullableRemoved value: -true - removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
get_network_logs8 fields changed- removed
Input schema / properties / clear / nullableRemoved value: -true - removed
Input schema / properties / include_details / nullableRemoved value: -true - removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true - removed
Input schema / properties / type_filter / nullableRemoved value: -true - removed
Input schema / properties / url_filter / nullableRemoved value: -true - removed
Input schema / properties / ws_content_filter / nullableRemoved value: -true - removed
Input schema / properties / ws_direction_filter / nullableRemoved value: -true
- Changed
get_performance_metrics2 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
inspect_dom5 fields changed- removed
Input schema / properties / after / nullableRemoved value: -true - removed
Input schema / properties / before / nullableRemoved value: -true - removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / query / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
list_tabs1 field changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true
- Changed
navigate2 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
open_instance7 fields changed- added
Input schema / properties / features / items / enumAdded value: +[ + "WEB_MCP", + "WEBGL_SOFTWARE" +] - removed
Input schema / properties / features / items / oneOfRemoved value: -[ - { - "enum": [ - "WEB_MCP" - ] - }, - { - "enum": [ - "WEBGL_SOFTWARE" - ] - } -] - added
Input schema / properties / features / items / typeAdded value: +"string" - removed
Input schema / properties / features / nullableRemoved value: -true - removed
Input schema / properties / headless / nullableRemoved value: -true - removed
Input schema / properties / label / nullableRemoved value: -true - removed
Input schema / properties / proxy / nullableRemoved value: -true
- Changed
open_tab3 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / label / nullableRemoved value: -true - removed
Input schema / properties / url / nullableRemoved value: -true
- Changed
pause_on_load2 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
profile_page_performance5 fields changed- removed
Input schema / properties / action / nullableRemoved value: -true - removed
Input schema / properties / disable_cache / nullableRemoved value: -true - removed
Input schema / properties / duration_ms / nullableRemoved value: -true - removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
reload2 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
remove_breakpoint2 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
restart_chrome6 fields changed- added
Input schema / properties / features / items / enumAdded value: +[ + "WEB_MCP", + "WEBGL_SOFTWARE" +] - removed
Input schema / properties / features / items / oneOfRemoved value: -[ - { - "enum": [ - "WEB_MCP" - ] - }, - { - "enum": [ - "WEBGL_SOFTWARE" - ] - } -] - added
Input schema / properties / features / items / typeAdded value: +"string" - removed
Input schema / properties / features / nullableRemoved value: -true - removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / proxy_server / nullableRemoved value: -true
- Changed
resume2 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
scroll6 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / pages / nullableRemoved value: -true - removed
Input schema / properties / selector / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true - removed
Input schema / properties / x / nullableRemoved value: -true - removed
Input schema / properties / y / nullableRemoved value: -true
- Changed
search_scripts2 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
send_cdp_command3 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / params / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
set_breakpoint6 fields changed- removed
Input schema / properties / column_number / nullableRemoved value: -true - removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / script_hash / nullableRemoved value: -true - removed
Input schema / properties / script_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true - removed
Input schema / properties / url / nullableRemoved value: -true
- Changed
step_over2 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
stop_chrome1 field changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true
- Changed
switch_tab2 fields changed- removed
Input schema / properties / activate / nullableRemoved value: -true - removed
Input schema / properties / instance_id / nullableRemoved value: -true
- Changed
webmcp_get_invocation2 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
webmcp_invoke_tool1 field changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true
- Changed
webmcp_list_invocations3 fields changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true - removed
Input schema / properties / status / nullableRemoved value: -true - removed
Input schema / properties / tab_id / nullableRemoved value: -true
- Changed
webmcp_list_tools1 field changed- removed
Input schema / properties / instance_id / nullableRemoved value: -true
35 tool updates
v1.0.11- Changed
capture_screenshot2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Changed
click_element2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Added
close_instance - Added
close_tab - Changed
enable_proxy_auth2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Changed
evaluate_js2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Changed
evaluate_on_call_frame2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Changed
fill_input2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Added
get_console_logs - Changed
get_custom_events2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Added
get_network_logs - Added
get_performance_metrics - Changed
inspect_dom2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Added
list_instances - Added
list_tabs - Changed
navigate2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Added
open_instance - Added
open_tab - Changed
pause_on_load2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Changed
profile_page_performance2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Changed
reload2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Added
remove_breakpoint - Changed
restart_chrome2 fields changed- added
Input schema / properties / featuresAdded value: +{ + "description": "Chrome capability presets to enable on the new instance. Constraints: closed set - 'WEB_MCP' turns on the experimental WebMCP surface for sites that expose tools to the browser; 'WEBGL_SOFTWARE' forces SwiftShader software WebGL for GPU-less environments. Arbitrary Chrome flags are not accepted. Interactions: presets apply only to the instance started by this call and are cleared by a later restart that omits them. Defaults to: [] (no presets).", + "items": { + "oneOf": [ + { + "enum": [ + "WEB_MCP" + ] + }, + { + "enum": [ + "WEBGL_SOFTWARE" + ] + } + ] + }, + "nullable": true, + "type": "array" +} - added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +}
- Added
resume - Added
scroll - Changed
search_scripts2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Changed
send_cdp_command2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Added
set_breakpoint - Changed
step_over2 fields changed- added
Input schema / properties / instance_idAdded value: +{ + "description": "Chrome instance id from open_instance/list_instances. Omit for the default instance.", + "nullable": true, + "type": "string" +} - added
Input schema / properties / tab_idAdded value: +{ + "description": "The Tab ID of the target tab. Omit to use the active tab.", + "nullable": true, + "type": "string" +}
- Added
stop_chrome - Added
switch_tab - Added
webmcp_get_invocation - Added
webmcp_invoke_tool - Added
webmcp_list_invocations - Added
webmcp_list_tools
8 tool updates
v1.0.10- Removed
get_console_logs - Removed
get_network_logs - Removed
get_performance_metrics - Removed
remove_breakpoint - Removed
resume - Removed
scroll - Removed
set_breakpoint - Removed
stop_chrome
18 tool updates
v1.0.7- Changed
capture_screenshot3 fields changed- changed
Input schema / properties / format / descriptionPrevious value: -"Optional: Image format. Valid options: \"png\", \"jpeg\", \"webp\". Defaults to \"png\"."New value: +"Output image format. Constraints: must be 'png', 'jpeg', or 'webp'. Interactions: 'quality' applies only to 'jpeg' and 'webp' formats. Defaults to: \"png\"." - changed
Input schema / properties / full_page / descriptionPrevious value: -"Optional: Capture the full page layout (beyond the visible viewport). Defaults to false."New value: +"Capture the entire page beyond visible viewport. Constraints: boolean value. Interactions: if true, captures full page height; if false, captures only visible area. Defaults to: false." - changed
Input schema / properties / quality / descriptionPrevious value: -"Optional: JPEG or WEBP compression quality (0-100)."New value: +"Compression quality (0-100, higher=better quality). Constraints: integer between 0 and 100. Interactions: only applies when 'format' is 'jpeg' or 'webp'; ignored for 'png'. Defaults to: 100."
- Changed
click_element1 field changed- changed
Input schema / properties / selector / descriptionPrevious value: -"CSS selector for the element to click"New value: +"CSS selector identifying the target element. Constraints: valid CSS selector string matching a single DOM element. Interactions: must resolve to exactly one visible element or operation fails. Defaults to: None (required)."
- Changed
enable_proxy_auth4 fields changed- added
Input schema / properties / password / descriptionAdded value: +"Proxy authentication password. Constraints: non-empty string. Interactions: paired with 'username'; sent to proxy server on auth challenge." - added
Input schema / properties / prewarm_url / descriptionAdded value: +"URL to navigate for proxy pre-warming. Constraints: valid URL (http/https). Interactions: navigated after auth setup to trigger proxy auth flow. Defaults to: \"http://api.ipify.org?format=json\"." - added
Input schema / properties / resource_type / descriptionAdded value: +"Resource type to intercept. Constraints: 'Document', 'Image', 'Script', 'XHR', etc. (Chrome CDP resource types). Interactions: filters which request types trigger auth handling. Defaults to: \"Document\"." - added
Input schema / properties / username / descriptionAdded value: +"Proxy authentication username. Constraints: non-empty string. Interactions: paired with 'password'; sent to proxy server on auth challenge."
- Changed
evaluate_js1 field changed- added
Input schema / properties / expression / descriptionAdded value: +"JavaScript code expression to execute. Constraints: valid JavaScript (single expression or IIFE). Interactions: automatically awaits promises; 'returnByValue' returns serialized results. Defaults to: None (required)."
- Changed
evaluate_on_call_frame1 field changed- added
Input schema / properties / expression / descriptionAdded value: +"JavaScript expression to evaluate in call frame scope. Constraints: valid JavaScript accessing local/closure variables. Interactions: requires active paused debugger session; has access to function parameters and local variables. Defaults to: None (required)."
- Changed
fill_input2 fields changed- changed
Input schema / properties / selector / descriptionPrevious value: -"CSS selector for the input element to fill"New value: +"CSS selector identifying the input element. Constraints: valid CSS selector matching an input/textarea/contenteditable element. Interactions: element must be focusable and writable. Defaults to: None (required)." - changed
Input schema / properties / text / descriptionPrevious value: -"The text to insert into the input field"New value: +"Text content to insert. Constraints: any string (special chars escaped automatically). Interactions: replaces any existing text after focus; triggers input/change events. Defaults to: None (required)."
- Changed
get_console_logs2 fields changed- changed
Input schema / properties / clear / descriptionPrevious value: -"If true, clears the internal console logs cache after retrieving the current logs. Use this to reset the state and only capture new logs going forward."New value: +"Clear console cache after returning logs. Constraints: boolean. Interactions: when true, subsequent calls only return new messages. Defaults to: false." - changed
Input schema / properties / level_filter / descriptionPrevious value: -"Optional level filter (e.g., \"error\", \"warning\", \"info\", \"log\")."New value: +"Filter logs by severity level (case-insensitive). Constraints: 'error', 'warning', 'info', 'log', or similar CDP log level. Interactions: when provided, returns only matching level; empty returns all. Defaults to: None (no filtering)."
- Changed
get_custom_events2 fields changed- changed
Input schema / properties / filter_method / descriptionPrevious value: -"Optional: Filter events by method name (e.g., 'Target.targetCreated')."New value: +"Filter events by CDP method name (case-sensitive). Constraints: string matching format 'Domain.eventName'. Interactions: when omitted, returns all events. Defaults to: None (no filtering)." - changed
Input schema / properties / limit / descriptionPrevious value: -"Optional: Limit the number of events returned (default 100)."New value: +"Maximum number of events to return. Constraints: positive integer (0 = unlimited, clamped to cache size). Interactions: limits result set size. Defaults to: 100."
- Changed
get_network_logs6 fields changed- changed
Input schema / properties / clear / descriptionPrevious value: -"If true, clears the internal network logs cache after retrieving the current logs. Use this to reset the state and only capture new traffic going forward."New value: +"Clear network cache after returning logs. Constraints: boolean. Interactions: when true, subsequent calls return only new traffic. Defaults to: false." - changed
Input schema / properties / include_details / descriptionPrevious value: -"If true (default), returns full details including request/response headers, response bodies for REST, and full payloads for WebSockets. If false, returns a summary containing only the URL, method, status, statusText, and resourceType (or payload length for WS). Set to false when you just need to survey what requests were made without downloading all their contents."New value: +"Include full request/response details. Constraints: boolean. Interactions: when false, returns summary only (URL, method, status); when true, includes headers, bodies. Defaults to: true." - changed
Input schema / properties / type_filter / descriptionPrevious value: -"Select the type of network traffic to retrieve. Valid options: \"rest\" (only REST/HTTP requests), \"websocket\" (only WebSocket frames), or \"both\" (default)."New value: +"Traffic type to include. Constraints: 'rest', 'websocket', or 'both' (case-insensitive). Interactions: limits results to specified type. Defaults to: \"both\"." - changed
Input schema / properties / url_filter / descriptionPrevious value: -"Filter by URL content. Only requests or WebSocket connections whose URL contains this exact string (case-insensitive) will be returned. Leave empty to disable URL filtering."New value: +"Partial URL match (case-insensitive). Constraints: non-empty string. Interactions: filters both REST and WebSocket URLs; empty string disables filtering. Defaults to: None (no URL filtering)." - changed
Input schema / properties / ws_content_filter / descriptionPrevious value: -"Filter WebSocket frames by their payload content. Only frames whose payload data contains this exact string (case-insensitive) will be returned."New value: +"WebSocket payload substring match (case-insensitive). Constraints: non-empty string. Interactions: applies only when type_filter includes 'websocket'; filters by payload content. Defaults to: None (no content filtering)." - changed
Input schema / properties / ws_direction_filter / descriptionPrevious value: -"Filter WebSocket frames by their transmission direction. Valid options: \"sent\" (client to server), \"received\" (server to client), or \"both\" (default)."New value: +"WebSocket frame direction filter. Constraints: 'sent', 'received', or 'both'. Interactions: applies only when type_filter includes 'websocket'. Defaults to: \"both\"."
- Changed
inspect_dom3 fields changed- changed
Input schema / properties / after / descriptionPrevious value: -"Optional: Number of characters to include after the match (default 200)"New value: +"Characters to include after the match. Constraints: non-negative integer. Interactions: only applies if 'query' provided. Defaults to: 200." - changed
Input schema / properties / before / descriptionPrevious value: -"Optional: Number of characters to include before the match (default 200)"New value: +"Characters to include before the match. Constraints: non-negative integer. Interactions: only applies if 'query' provided. Defaults to: 200." - changed
Input schema / properties / query / descriptionPrevious value: -"Optional: Search for this specific text within the DOM"New value: +"Text pattern to search for in the DOM (case-sensitive). Constraints: any string. Interactions: when provided, returns context snippet instead of full HTML. Defaults to: None (returns full HTML if omitted)."
- Changed
navigate1 field changed- added
Input schema / properties / url / descriptionAdded value: +"Target URL to navigate to. Constraints: valid absolute URL (http/https/file). Interactions: navigation is blocked if MCP server started with 'local' flag and URL is not localhost/127.0.0.1/192.168.x.x/*.local. Defaults to: None (required)."
- Changed
profile_page_performance3 fields changed- changed
Input schema / properties / action / descriptionPrevious value: -"Action to perform right after starting the trace. Can be \"none\" (default) or \"reload\"."New value: +"Action to trigger during tracing. Constraints: 'none' or 'reload'. Interactions: 'reload' restarts page recording from initial load (useful with disable_cache=true). Defaults to: \"none\"." - changed
Input schema / properties / disable_cache / descriptionPrevious value: -"If true, disables the network cache before profiling and restores it after. Useful with action=\"reload\" to simulate a cold start."New value: +"Disable network cache during trace. Constraints: boolean. Interactions: when true with action='reload', simulates cold start; cache restored after profiling. Defaults to: false." - changed
Input schema / properties / duration_ms / descriptionPrevious value: -"Duration to record the trace in milliseconds. Defaults to 3000ms. Keep it between 1000 and 10000."New value: +"Recording duration in milliseconds. Constraints: integer between 500 and 15000. Interactions: longer duration captures more data; use 3000-5000 for typical pages. Defaults to: 3000."
- Changed
remove_breakpoint1 field changed- added
Input schema / properties / breakpoint_id / descriptionAdded value: +"Unique identifier of the breakpoint (returned from set_breakpoint). Constraints: non-empty string matching format from set_breakpoint response. Interactions: must correspond to an active breakpoint or operation will fail."
- Changed
restart_chrome1 field changed- added
Input schema / properties / proxy_server / descriptionAdded value: +"Proxy server URL (e.g., 'http://proxy.example.com:8080'). Constraints: valid proxy URL with protocol and port. Interactions: applied to new Chrome instance; requires 'enable_proxy_auth' for authenticated proxies. Defaults to: None (no proxy)."
- Changed
scroll4 fields changed- changed
Input schema / properties / pages / descriptionPrevious value: -"Optional: Number of viewport heights to scroll vertically"New value: +"Number of viewport heights to scroll vertically. Constraints: positive float (e.g., 1.5 = 1.5× viewport height). Interactions: takes precedence over 'y' parameter if both provided; ignored if 'selector' provided. Defaults to: None." - changed
Input schema / properties / selector / descriptionPrevious value: -"Optional: CSS selector of the element to scroll into view"New value: +"CSS selector of element to scroll into view. Constraints: valid CSS selector string. Interactions: takes precedence over 'x', 'y', 'pages' if provided; fails if element not found. Defaults to: None." - changed
Input schema / properties / x / descriptionPrevious value: -"Optional: Number of pixels to scroll horizontally (positive for right, negative for left)"New value: +"Horizontal scroll distance in pixels. Constraints: integer (positive=right, negative=left). Interactions: ignored if 'selector' is provided; combined with 'y' for diagonal scrolling. Defaults to: 0 (no horizontal scroll)." - changed
Input schema / properties / y / descriptionPrevious value: -"Optional: Number of pixels to scroll vertically (positive for down, negative for up)"New value: +"Vertical scroll distance in pixels. Constraints: integer (positive=down, negative=up). Interactions: ignored if 'selector' or 'pages' is provided; overridden by 'pages'. Defaults to: 0 (no vertical scroll)."
- Changed
search_scripts1 field changed- added
Input schema / properties / query / descriptionAdded value: +"Text pattern or special command to search for. Constraints: non-empty string (empty string returns cached script count). Interactions: '@source' returns first 1000 chars of each script; 'debug' returns script lengths and errors. Defaults to: None (required)."
- Changed
send_cdp_command2 fields changed- changed
Input schema / properties / method / descriptionPrevious value: -"The CDP method name (e.g., 'DOM.getDocument')."New value: +"CDP protocol method name (e.g., 'DOM.getDocument', 'Runtime.evaluate'). Constraints: valid CDP domain.method format. Interactions: method must be recognized by Chrome protocol version." - changed
Input schema / properties / params / descriptionPrevious value: -"A JSON string representing the parameters for the CDP command (e.g., '{\"url\": \"https://example.com\"}'). Omit or provide '{}' if no parameters are needed."New value: +"JSON-formatted parameters for the CDP command. Constraints: valid JSON object string. Interactions: Page.navigate URLs subject to local-only restrictions; empty string or '{}' for no parameters. Defaults to: None."
- Changed
set_breakpoint5 fields changed- added
Input schema / properties / column_number / descriptionAdded value: +"Column number within the line. Constraints: non-negative integer. Interactions: optional; narrower precision if provided. Defaults to: start of line (0)." - added
Input schema / properties / line_number / descriptionAdded value: +"Line number where breakpoint is set (0-indexed). Constraints: non-negative integer, must be within script bounds. Interactions: required parameter; combined with 'column_number' to pinpoint exact location." - added
Input schema / properties / script_hash / descriptionAdded value: +"Script hash to identify the target script. Constraints: one of 'script_hash', 'script_id', or 'url' must be provided. Defaults to: None." - added
Input schema / properties / script_id / descriptionAdded value: +"Script ID (from Debugger.scriptParsed event). Constraints: one of 'script_hash', 'script_id', or 'url' must be provided. Interactions: mutually exclusive with 'script_hash' and 'url' (first match wins). Defaults to: None." - added
Input schema / properties / url / descriptionAdded value: +"Script URL to match. Constraints: one of 'script_hash', 'script_id', or 'url' must be provided. Interactions: mutually exclusive with 'script_hash' and 'script_id'. Defaults to: None."
24 tool updates
v1.0.0- First observed
capture_screenshot - First observed
click_element - First observed
enable_proxy_auth - First observed
evaluate_js - First observed
evaluate_on_call_frame - First observed
fill_input - First observed
get_console_logs - First observed
get_custom_events - First observed
get_network_logs - First observed
get_performance_metrics - First observed
inspect_dom - First observed
navigate - First observed
pause_on_load - First observed
profile_page_performance - First observed
reload - First observed
remove_breakpoint - First observed
restart_chrome - First observed
resume - First observed
scroll - First observed
search_scripts - First observed
send_cdp_command - First observed
set_breakpoint - First observed
step_over - First observed
stop_chrome
TDQS
Scored across 30 tools
The tools target largely distinct resource+action pairs (breakpoint control, tab/instance lifecycle, DOM interaction, observability). The only mild overlaps are stop_chrome vs close_instance and get_performance_metrics vs profile_page_performance, but descriptions clearly differentiate the destructive/scope differences. No tool appears to duplicate another's purpose.
Names overwhelmingly follow a consistent snake_case verb_noun pattern (set_breakpoint, list_tabs, open_instance, get_network_logs). A handful of single-verb names (resume, reload, navigate, scroll) deviate slightly but remain clear and readable.
At 30 tools this is on the heavy side, above the comfortable 15-tool range. However, the surface spans four genuinely distinct domains (instances, tabs, DOM/debugger, observability) plus two raw escape hatches, so most tools map to real capabilities rather than filler. Borderline but defensible.
Coverage is strong: instance open/stop/restart/close/list, tab open/close/switch/list, DOM inspection, click/fill/scroll, full debugger stepping and breakpoints, plus network/console/perf observability and CDP escape hatches. Minor gaps like dialog/file-upload/cookie handling remain, but core debug workflows are complete.
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