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JS Reverse MCP

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AI-first / AI-native 的 JavaScript 逆向工程 MCP Server,让你的 AI 编码助手(如 Claude、Cursor、Copilot)能够像分析师一样持续调试、定位、保存和复盘网页中的 JavaScript 行为。

它不是把 Chrome DevTools API 原样搬给模型,而是把脚本、断点、网络、WebSocket、浏览器状态和本地文件 I/O 重新组织成适合 AI Agent 连续推理和操作的工具。反检测是其中一部分能力:默认使用为本 MCP 重新编译发布、独立维护的 Patchright fork 提供协议层 stealth,对强反爬站点可选启用 CloakBrowser 源码层指纹模式。

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Related MCP server: Chrome DevTools MCP

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感谢 Infistar.cc 无限星河赞助并为 js-reverse-mcp 提供模型服务支持!

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  • 🧠 一个 API Key 接入主流模型:支持 ChatGPT、Claude、Gemini、Kimi、GLM、DeepSeek 等模型,适配 Claude Code、Codex、Cursor 等 AI 编程工具。

  • 🔎 助力授权调试与安全研究:适用于脚本检索、断点分析、网络请求追踪、调用栈检查和代码逻辑理解等多步骤任务。

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定位:Claude Code / Codex 模型 API 配置支持。

功能特点

  • AI-native 工具设计:工具粒度、输出边界和错误提示都围绕 Agent 决策设计,避免把模型推向无效下一步

  • 可复盘工作流:脚本源码、网络原始数据、二进制结果都能导出到本地文件,再作为后续分析输入

  • 断点上下文执行:暂停时可直接在 call frame 中求值,检查作用域变量,单步执行并返回源码上下文

  • 脚本分析:列出所有加载的 JS,搜索代码,获取/保存源码,自动格式化大型压缩脚本

  • 网络与 WebSocket 分析:请求调用栈、XHR 断点、Set-Cookie 识别、原始 body/header 导出、WebSocket 消息分组

  • 浏览器状态重放:清理当前站点 cookies / cache / storage / sessionStorage,配合 reload 复现 cookie 和风控流程

  • 默认有头 + 持久化登录态:看得到浏览器,cookies / localStorage 跨会话保留

  • 专用 Patchright 内核:默认依赖本项目独立维护的 Patchright fork,持续修复上游已知的共享实现特征

  • 可选反检测层:专用 Patchright 协议层 stealth 默认启用;强反爬站点可加 --cloak 使用 CloakBrowser 二进制

专用 Patchright fork

js-reverse-mcp 不再直接依赖 Patchright 的大众发行包,而是使用专门为本 MCP 编译发布的 @zhizhuodemao/patchright。这个 fork 会在独立仓库持续维护,并随本 MCP 的实际检测样本演进。

  • 不再直接依赖 Patchright 大众发行包

  • 针对已确认的上游共享实现特征进行协议层调整并重新编译发布

  • 反检测调整不依赖页面级 JS 注入

  • 保留 evaluate、locator 和页面控制等原始能力

  • fork 在面向本 MCP 的专用仓库中持续维护

公开文档仅说明设计边界,不展开内部检测样本与实现细节。专用 fork 的目标是减少已确认的共享实现特征,而不是承诺浏览器自动化绝对不可检测。

系统要求

快速开始(npx)

无需安装,直接在 MCP 客户端配置中添加:

{
  "mcpServers": {
    "js-reverse": {
      "command": "npx",
      "args": ["js-reverse-mcp"]
    }
  }
}

Claude Code

claude mcp add js-reverse npx js-reverse-mcp

如果你还没有可用的模型 API,或者需要配置自定义 API 地址,可以参考:Claude Code / Codex 第三方模型 API 配置教程。

Codex

codex mcp add js-reverse -- npx js-reverse-mcp

如果你还没有可用的模型 API,或者需要配置自定义 API 地址,可以参考:Claude Code / Codex 第三方模型 API 配置教程。

Cursor

进入 Cursor Settings -> MCP -> New MCP Server,使用上面的配置。

VS Code Copilot

code --add-mcp '{"name":"js-reverse","command":"npx","args":["js-reverse-mcp"]}'

本地安装(可选)

git clone https://github.com/zhizhuodemao/js-reverse-mcp.git
cd js-reverse-mcp
npm install
npm run build

然后在 MCP 配置中使用本地路径:

{
  "mcpServers": {
    "js-reverse": {
      "command": "node",
      "args": ["/你的路径/js-reverse-mcp/build/src/index.js"]
    }
  }
}

AI-first 设计

这个项目的核心目标不是“能操作浏览器”,而是让 AI Agent 能稳定完成一轮真实 JS 逆向任务:打开页面、过风控、定位脚本、保存源码、设置断点、触发行为、检查运行时、导出网络材料、复现状态,然后继续推理。

几个设计取向贯穿在代码里:

  • 工具是 Agent primitives,不是 DevTools 菜单映射:list_network_requests 既能列索引,也能按 reqid 查详情,还能用 outputFile 导出精确材料;evaluate_script 既能在页面执行,也能在断点 call frame 执行,还能接收 localFilePath 输入。

  • 输出要能指导下一步:列表输出保持短而可扫描;详情输出有边界;长结果提示导出;pending 请求会明确提示先恢复执行,避免 Agent 等一个永远不会完成的 response。

  • 本地文件是分析工作台:save_script_source、list_network_requests(..., outputFile)、evaluate_script(..., localFilePath) 让 Agent 能在浏览器、网络和本地文件之间往返,而不是把大段代码或二进制数据塞进聊天上下文。

  • 状态可清理、流程可重放:默认 profile 保留登录态;--isolated 提供一次性干净环境;clear_site_data 只清当前站点相关状态,用来反复复现 cookie 生成、风控初始化和请求链路。

  • 反检测服务于调试链路:CDP 静默导航、真实视口、Google referer、专用 Patchright fork 和 CloakBrowser 的目标都是让 Agent 能进入目标页面继续分析,而不是把项目变成一个泛用爬虫框架。

反检测机制(支撑能力)

反检测是 js-reverse-mcp 的底层支撑能力之一。包装层(这个 MCP 自己)零 JS 注入、不做 Object.defineProperty hack(那本身就是检测信号)。所有反检测都在两个互不重叠的层:

层

默认模式

--cloak 模式

协议层(CDP)

专用 Patchright fork:不调 Runtime.enable / Console.enable,在 isolated world 里执行 evaluate,移除自动化 launch flag,并持续修复已知共享实现特征

同

源码层(C++ 二进制 patch)

无 —— 直接用系统 Google Chrome

CloakBrowser 二进制(按平台提供源码层指纹 patch,覆盖 navigator.webdriver、canvas、WebGL、audio、GPU、字体、屏幕、WebRTC、TLS)

Profile 目录

~/.cache/chrome-devtools-mcp/chrome-profile(持久化登录态)

~/.cache/chrome-devtools-mcp/cloak-profile(与默认物理隔离)

实际浏览器

你装的 Google Chrome(带 Web Store、扩展、sync)

定制 Chromium 编译版(无 Google 服务、无 Web Store)

另外几个导航级措施(两种模式都生效):

  • CDP 静默导航 —— 页面加载时不激活 Network.enable / Debugger.enable,请求/控制台收集只走 Playwright 监听器,直到某个工具显式需要 CDP 才激活

  • Google Referer —— new_page 默认带 referer: https://www.google.com/

  • 真实视口 —— 关掉 Playwright 默认的 1280×720 假视口,浏览器展示真实屏幕尺寸

何时开 --cloak:只在以上还不够、被站点指纹拦截时才用。详见 docs/cloak.md。

工具列表(24 个)

页面与导航

工具

描述

select_page

列出打开的页面,或按索引选择调试上下文

new_page

创建新页面并导航到 URL

navigate_page

导航、后退、前进或刷新页面

select_frame

列出所有 frame(iframe),或选择执行上下文

click_element

严格匹配并点击当前 frame 中的单个可见元素

take_screenshot

截取页面截图

脚本分析

工具

描述

list_scripts

列出页面中所有加载的 JavaScript 脚本

get_script_source

获取脚本源码片段,支持行范围或字符偏移

save_script_source

保存完整脚本源码到本地文件(适用于大型/压缩/WASM文件)

search_in_sources

在所有脚本中搜索字符串或正则表达式

断点与执行控制

工具

描述

set_breakpoint_on_text

通过搜索代码文本自动设置断点(适用于压缩代码)

break_on_xhr

按 URL 模式设置 XHR/Fetch 断点

remove_breakpoint

用显式 action 按 ID、URL 或全部移除断点

list_breakpoints

列出所有活动断点

get_paused_info

获取暂停状态、调用栈和作用域变量

pause_or_resume

用显式 action 暂停或恢复执行

step

单步调试(over/into/out),返回位置和源码上下文

网络与 WebSocket

工具

描述

list_network_requests

列出网络请求、查看详情,或导出 header/body/query 等原始材料

clear_network_requests

显式确认后清空当前页面已收集的请求和 body cache

get_request_initiator

获取网络请求的 JavaScript 调用栈

get_websocket_messages

列出 WebSocket 连接、分析消息模式或获取消息详情

浏览器状态

工具

描述

clear_site_data

清理当前站点相关 cookies、origin storage 和 sessionStorage;可显式选择清理全局 HTTP cache

检查工具

工具

描述

evaluate_script

在页面或断点上下文执行 JavaScript,支持主世界、保存结果和读取一个本地输入文件

list_console_messages

列出控制台消息,或按 msgid 获取单条详情

使用示例

JS 逆向基本流程

  1. 打开目标页面

打开 https://example.com 并列出所有加载的 JS 脚本
  1. 查找目标函数

在所有脚本中搜索包含 "encrypt" 的代码
  1. 设置断点

在加密函数入口处设置断点
  1. 触发并分析

在页面上触发操作,断点命中后检查参数、调用栈和作用域变量

WebSocket 协议分析

列出 WebSocket 连接,分析消息模式,查看特定类型的消息内容

Agent 推荐的完整捕获流程

因为导航阶段会刻意保持 CDP 静默,首次进入目标页时不会立即打开 Network / Debugger 域。推荐流程是先过风控,再刷新捕获:

1. new_page 打开目标页
2. 调用 list_network_requests 激活 collectors
3. navigate_page(type="reload") 刷新页面
4. 再次 list_network_requests 查看完整请求
5. 对关键 reqid 使用 outputFile 导出原始材料
1. clear_site_data(confirm=true) 清理当前站点状态
2. navigate_page(type="reload") 重新触发初始化
3. list_network_requests 找到设置 cookie 或提交 sensor 的请求
4. 导出 requestBody / responseHeaders / responseBody
5. 用 evaluate_script + localFilePath 在页面上下文中复算或验证

配置选项

CLI 保持精简,所有 flag 都是可选项。99% 场景默认即可。涉及本地文件时,建议用 --allowedRoots 限定 Agent 可读写的目录。

选项

描述

默认值

--cloak

切换到 CloakBrowser 隐身二进制(取代系统 Chrome)。启用按平台提供的 C++ 源码层指纹 patch。首次启动自动下载 ~200MB 二进制;指纹身份按 profile 持久化。详见 docs/cloak.md。

false

--isolated

使用临时 user-data-dir(cookies/localStorage 不保留,关闭时自动清理)

false

--browserUrl, -u

连接到已运行的 Chrome 实例(CDP HTTP 端点,如 http://127.0.0.1:9222)。MCP 会自动探测出 WebSocket debugger URL。本地 Chrome、AdsPower、BitBrowser 等怎么拿到这个端点详见 docs/cdp-endpoint.md。

–

--logFile

写入 0600 普通文件的 MCP 调试日志;详细日志仅使用 DEBUG=mcp:*。不要使用 DEBUG=*,浏览器协议日志可能泄露页面、Cookie、脚本和凭据。

–

--allowedRoots

可重复指定 Agent 允许读写的本地目录;解析真实路径并拒绝符号链接越界。启用时禁用 file:、view-source:file: 和 filesystem:file: 浏览器页面。未指定时本地文件访问不受目录限制,启动时会打印安全警告。

–

示例配置

默认 —— 系统 Chrome + 持久化登录态(绝大多数调试场景推荐):

{
  "mcpServers": {
    "js-reverse": {
      "command": "npx",
      "args": ["js-reverse-mcp"]
    }
  }
}

--cloak —— 强反爬站点(Cloudflare Turnstile / DataDome / FingerprintJS 防护):

强烈推荐:先把二进制预下载好(一次性,~30–60 秒)。不做这一步的话,首次启动带 --cloak 的 MCP 会静默下载 ~200MB,看起来像 MCP 卡住了:

npx cloakbrowser install

(cloakbrowser 包已经通过 optionalDependencies 一起装好,这条命令只是触发它自带的二进制下载逻辑,有进度条)

{
  "mcpServers": {
    "js-reverse-cloak": {
      "command": "npx",
      "args": ["js-reverse-mcp", "--cloak"]
    }
  }
}

两套并行 —— 两个 MCP 实例 profile 物理隔离,根据目标站点切换:

{
  "mcpServers": {
    "js-reverse": {
      "command": "npx",
      "args": ["js-reverse-mcp"]
    },
    "js-reverse-cloak": {
      "command": "npx",
      "args": ["js-reverse-mcp", "--cloak"]
    }
  }
}

--isolated —— 每次全新 profile(不保留 cookies/localStorage):

{
  "mcpServers": {
    "js-reverse": {
      "command": "npx",
      "args": ["js-reverse-mcp", "--isolated"]
    }
  }
}

连接到已运行的 Chrome / 第三方指纹浏览器

--browserUrl 只接受 CDP endpoint(能响应 /json/version 的 HTTP 端点),不接受厂商私有 Local API。本地 Chrome、AdsPower、BitBrowser 等场景下怎么拿到 CDP 端口,详见专门的文档:

📖 docs/cdp-endpoint.md —— 如何拿到 CDP 调试端口

最短路径(本地 Chrome):

# 先关掉所有 Chrome 窗口,然后
/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome \
  --remote-debugging-port=9222 --user-data-dir=/tmp/chrome-debug
{
  "mcpServers": {
    "js-reverse": {
      "command": "npx",
      "args": ["js-reverse-mcp", "--browserUrl", "http://127.0.0.1:9222"]
    }
  }
}

指纹浏览器(AdsPower、BitBrowser 等)的 CDP 端口是每次启动随机变化的,必须通过厂商 Local API 启动浏览器后再提取,操作步骤和示例脚本都在上面那篇文档里。

故障排除

被反爬系统拦截

如果访问某些站点被拦截(如知乎返回 40362、Cloudflare 挑战死循环):

  1. 先试 --isolated —— 用全新 profile 排除残留状态污染:

    "args": ["js-reverse-mcp", "--isolated"]
  2. 还不行就开 --cloak —— 启用按平台提供的源码层指纹 patch:

    "args": ["js-reverse-mcp", "--cloak"]
  3. 最后再考虑手动清持久化 profile(会丢登录态):

    rm -rf ~/.cache/chrome-devtools-mcp/chrome-profile

什么时候该开 --cloak、什么时候不该开,详见 docs/cloak.md。

Agent 路由评测(维护者)

npm run eval:routing:validate 会离线校验实际 MCP tools/list、server instructions 与 evals/tool-routing.json 的 30 条工具选择契约;该命令不会访问模型端点,并已纳入 presubmit。

真实模型评测是显式 opt-in,会逐条调用 OpenAI-compatible Chat Completions 端点并可能产生费用:

MCP_ROUTING_EVAL_ENDPOINT=https://api.example.com/v1/chat/completions \
MCP_ROUTING_EVAL_MODEL=model-name \
MCP_ROUTING_EVAL_API_KEY=secret \
npm run eval:routing

MCP_ROUTING_EVAL_API_KEY 对无需认证的本地端点可省略;带凭据的远程端点必须使用 HTTPS,HTTP 仅允许 loopback。可用 MCP_ROUTING_EVAL_TIMEOUT_MS 调整单条请求超时。默认要求 100% 通过,跨模型对比时可用 MCP_ROUTING_EVAL_MIN_PASS_RATE 设置 (0, 1] 阈值。评测不会输出 API key、endpoint 或端点错误响应正文。

安全提示

此工具会将浏览器内容暴露给 MCP 客户端,允许检查、调试和修改浏览器中的任何数据。请勿在包含敏感信息的页面上使用。

evaluate_script.localFilePath、各类 outputFile/filePath 会让 MCP 进程读取或写入宿主机文件。生产或共享环境应使用一个或多个 --allowedRoots 收窄到专用工作目录;未配置时访问范围不受限制。启用 --allowedRoots 后,file:、view-source:file: 和 filesystem:file: 浏览器页面也会被拒绝,避免通过浏览器导航绕过目录边界;需要调试本地页面时,只能在明确接受本地文件暴露风险的会话中不配置该选项。

许可证

Apache-2.0

Available Tools

24 tools
break_on_xhrA

Sets a URL-substring breakpoint for a future XHR/Fetch when runtime request arguments, local variables, or payload construction must be inspected. For an already captured request, call get_request_initiator first because it is non-pausing; use this only when that evidence is insufficient. Set it before reproducing the user action—it does not inspect past traffic—then call get_paused_info/evaluate_script and finally step or resume. The URL pattern identifies this breakpoint for list_breakpoints and remove_breakpoint(action="remove_xhr").

NameRequiredDescriptionDefault
urlYesCase-sensitive URL substring matched against future XHR/Fetch requests. Prefer a narrow endpoint path from list_network_requests; retain the exact string to remove the breakpoint later.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNoMachine-readable result payload.
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.7/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations indicate mutation (readOnlyHint=false) and non-destructive (destructiveHint=false). Description adds that the breakpoint is for future requests only, does not inspect past traffic, and requires subsequent steps. Also explains how the URL pattern ties to list_breakpoints and remove_breakpoint.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Description is a single paragraph of about 100 words, front-loaded with purpose, then usage sequence, then relation to other tools. Every sentence contributes. Could be slightly more compact, but efficient overall.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the existence of an output schema, return values are not needed in description. Covers what, when, how, and parameter details. Could explicitly mention that the breakpoint causes a pause on request, but context is fairly complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema has one parameter 'url' with description. Tool description adds context: case-sensitive, should be a narrow endpoint path from list_network_requests, retain exact string for removal. This goes beyond the schema description. With 100% schema coverage, baseline is 3, but added value justifies 4.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose: setting a URL-substring breakpoint for future XHR/Fetch to inspect runtime arguments, variables, or payloads. It distinguishes from get_request_initiator, which handles already captured requests.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides explicit guidance: use when need to inspect request details at runtime, avoid for already captured requests (use get_request_initiator instead). Specifies the workflow: set before reproducing action, then call get_paused_info/evaluate_script, then step/resume. Also notes it does not inspect past traffic.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

clear_network_requestsA
DestructiveIdempotent

Discard captured HTTP(S) evidence for the currently selected page after confirm=true. Use this immediately before reproducing an action when a clean network capture window is needed; do not use it to reset login, cookies, cache, or other browser state. It irreversibly clears the in-memory request queue, cached response bodies, and initiator maps only. Browser cookies, HTTP cache, origin storage, console messages, and WebSocket connections/messages are unchanged; use clear_site_data for cookie and storage reset. New captures continue above the previous reqid high-water mark because reqids are never reused.

NameRequiredDescriptionDefault
confirmNoMust be true to irreversibly delete the selected page's captured request history, response-body cache, and initiator evidence. This confirms capture cleanup, not browser-state cleanup.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNoMachine-readable result payload.
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.9/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Despite destructiveHint=true annotation, description adds detail on what is irreversibly cleared (request queue, cached response bodies, initiator maps) and what is unchanged (cookies, HTTP cache, storage), exceeding annotation info.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Concise paragraph with front-loaded action, followed by usage guidance, behavioral specifics, and contrast with sibling; every sentence adds value with no redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given simple single-parameter tool with output schema, description fully covers purpose, usage, behavioral boundaries, and parameter semantics without missing critical context.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% for the single parameter 'confirm', and description reinforces its meaning as required for irreversible capture cleanup, adding nuance beyond schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Description uses specific verb 'discard' and resource 'captured HTTP(S) evidence', clearly distinguishing from sibling clear_site_data by stating what it does not affect.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly states when to use ('immediately before reproducing an action when a clean network capture window is needed') and when not to use ('do not use it to reset login, cookies, cache'), with reference to alternative clear_site_data.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

clear_site_dataA
DestructiveIdempotent

Irreversibly clear browser state after confirm=true to create a clean replay environment for the selected page. Use this before replaying login, session creation, storage initialization, or other state-dependent flows; do not use it to inspect cookies or determine which response set one. For cookie provenance, including HttpOnly, Secure, and SameSite attributes, use list_network_requests with cookieName first. Cleanup covers cookies affecting the selected page's HTTP(S) frames—including HttpOnly and Secure cookies through the browser context—persistent storage for those frame origins, and each HTTP(S) frame's sessionStorage. It does not reload the page. The browser HTTP cache is global and is preserved by default; set clearBrowserCache=true only when that wider cross-page effect is explicitly intended.

NameRequiredDescriptionDefault
confirmNoMust be true to irreversibly delete cookies affecting the selected page's HTTP(S) frames, persistent storage for those frame origins, and HTTP(S) frame sessionStorage. This confirms state reset for replay, not inspection.
clearBrowserCacheNoAlso clear the browser-wide HTTP cache. Leave false for site-scoped replay cleanup. Setting true has a wider global effect on every page and origin in this browser, not only the selected page or its frame origins.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNoMachine-readable result payload.
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.8/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description details what is cleared (cookies, persistent storage, sessionStorage) and what is not (page reload, HTTP cache by default), and explains the effect of clearBrowserCache. Annotations indicate destructiveHint=true and readOnlyHint=false, which align with 'irreversibly clear'; no contradiction.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is slightly verbose but front-loaded with the main purpose. Every sentence adds value, and the structure logically flows from purpose to usage to details.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the presence of an output schema (context: 'Has output schema: true'), the description does not need to explain return values. It covers purpose, usage, parameters, and behavioral details comprehensively for a complex tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, but the description adds meaning by explaining that confirm=true is required for irreversible action and that clearBrowserCache has a global effect, providing context beyond the schema descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool irreversibly clears browser state for a clean replay environment, specifying the verb ('clear') and resource ('browser state for selected page'). It distinguishes from sibling tool 'list_network_requests' for cookie inspection.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly states when to use ('before replaying login, session creation...') and when not to use ('do not use it to inspect cookies'), and provides an alternative tool ('list_network_requests') for cookie provenance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

click_elementA
Destructive

Performs one verified, auditable click in the currently selected frame. Use it when the task requires activating a known button, link, or control after selecting the correct page/frame and identifying a CSS selector; it is the preferred minimal interaction primitive over arbitrary evaluate_script code. It does not discover elements, type text, or silently guess among matches: the selector must resolve to exactly one element unless index is explicit, and the chosen element must be visible. A click can submit data, navigate, or trigger external effects, so confirm=true is required and the result reports the exact resolved element.

NameRequiredDescriptionDefault
indexNoExplicit zero-based match index. Required when the selector matches more than one element.
buttonNoMouse button. Defaults to left.left
confirmNoMust be true to authorize this specific click because it can submit data, navigate, or trigger external side effects.
timeoutNoMaximum wait time in milliseconds. If set to 0, the default timeout will be used.
selectorYesCSS selector evaluated only in the currently selected frame. Use select_frame first when the target is inside an iframe.
modifiersNoOptional keyboard modifiers held during the click.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNo
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.8/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations declare destructiveHint=true and openWorldHint=true, and the description adds substantive context: the selector must resolve to exactly one element unless index is given, the element must be visible, confirm=true is required, and clicks can submit data or navigate. It also discloses that the result reports the exact resolved element. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is front-loaded with purpose and then layered with usage, constraints, and safety context. It is slightly dense but every sentence contributes information an agent needs; no sentence is redundant filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The tool has an output schema, full annotation coverage, six parameters with 100% schema descriptions, and the description fills in the remaining behavioral gaps (uniqueness, visibility, confirmation, frame scoping). Nothing an agent needs to invoke it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, but the description adds semantic constraints beyond the schema: the one-element-match rule, the explicit visibility requirement, and the frame-selection prerequisite. It does not add new syntax details for modifiers or button, but those are already fully documented in the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Performs one verified, auditable click in the currently selected frame') and distinguishes the tool from evaluate_script and select_frame. An agent can tell exactly what this does and what it is not for.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly names the conditions for use ('after selecting the correct page/frame and identifying a CSS selector'), the preferred alternative ('over arbitrary evaluate_script code'), and the when-not cases ('does not discover elements, type text, or silently guess among matches'). 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.

evaluate_scriptA
Destructive

Evaluates one focused JavaScript function for DOM/page state, web storage, page-defined globals, a paused-frame expression, or browser-side processing of one local file. Use it when those runtime values are the goal and no narrower evidence tool applies. Do not use document.cookie or page evaluation to investigate HttpOnly/Secure cookies, Set-Cookie provenance, or captured HTTP evidence; use list_network_requests with cookieName/reqid, and use search_in_sources/get_script_source for source discovery. While running, evaluation uses the selected frame's isolated world by default or its page main world with mainWorld=true; while paused, it always uses the chosen call frame and ignores mainWorld. Call get_paused_info before paused evaluation, then step or resume when finished. Arbitrary code can change page/external state and requires confirm=true; inline results are bounded, so use outputFile for exact large or binary results.

NameRequiredDescriptionDefault
confirmNoMust be true to authorize this exact arbitrary-code evaluation, which may mutate page state, send requests, or cause external side effects. Prefer a read-only expression when inspection is sufficient.
functionYesJavaScript function declaration invoked by the tool, for example `() => document.title` or `async () => await Promise.resolve(location.href)`. Return JSON-serializable data; ArrayBuffer/typed arrays require outputFile for exact bytes. With localFilePath, accept `async ({localFile}) => ...` and read localFile.text for UTF-8 or localFile.base64 for exact bytes. Keep the function focused; use mainWorld=true only when page-defined globals are required.
mainWorldNoRunning-page mode only: false uses the selected frame's isolated context; true uses that frame's page main world to access application-defined globals. When execution is paused, evaluation always targets frameIndex and this option is ignored.
frameIndexNoPaused mode only: zero-based call frame from get_paused_info (default: top frame). The index and its callFrameId expire after any step or resume.
outputFileNoSave the exact result locally instead of returning bounded inline content. JSON-serializable values are written as JSON text and ArrayBuffer/typed arrays as raw bytes; the returned filename is resolved and subject to --allowedRoots.
localFilePathNoAbsolute path to one host file passed as localFile; the browser never reads the path directly. Running-page input is limited to 10 MiB, while paused call-frame input remains limited to 512 KiB. Relative paths, file:// URLs, globs, ~, and directories are rejected, access is subject to --allowedRoots, and file contents may expose sensitive host data.
confirmOverwriteNoSet true only to authorize replacing an existing outputFile. A new file does not require overwrite confirmation.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNo
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.6/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the annotations, the description explains isolated-world versus mainWorld execution, that paused evaluation always targets the chosen call frame and ignores mainWorld, that frame/callFrameId expire after stepping or resuming, and that arbitrary code can mutate page or external state and requires confirm=true. It also discloses bounded inline results and the outputFile workaround for large or binary data.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is dense and front-loads the core purpose, then adds usage, exclusions, runtime-mode caveats, and safety requirements. It is longer than typical, but nearly every sentence carries actionable information for a high-risk evaluation tool.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the dangerous, open-world nature of arbitrary code evaluation, the description covers intended use, prohibited use, execution contexts, paused-mode workflow, confirmation requirements, and large-result handling. With a rich input schema and output schema present, this is sufficiently complete for correct invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

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 seven parameters in detail. The description adds some useful cross-parameter context, such as paused mode ignoring mainWorld and using the selected call frame, but it largely repeats what the schema already provides.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb and resource: evaluating one focused JavaScript function for runtime values such as DOM state, web storage, globals, paused-frame expressions, or local-file processing. It clearly distinguishes the tool from sibling evidence tools by naming network-request and source-discovery alternatives.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives explicit use conditions ('when those runtime values are the goal and no narrower evidence tool applies') and explicit exclusions for cookies and source discovery. It routes the agent to list_network_requests, search_in_sources, and get_script_source, and states when to call get_paused_info before paused evaluation.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

get_paused_infoA
Read-only

Inspects the current call stack, source locations, and selected call-frame scopes after a code/XHR breakpoint or explicit pause has stopped execution. It neither creates a pause nor resumes one. Returned frameIndex values and callFrameIds belong only to the current pause and expire after any step or resume; use evaluate_script with frameIndex for a focused expression, then step or pause_or_resume(action="resume").

NameRequiredDescriptionDefault
frameIndexNoZero-based frame from this pause whose scopes should be read (default: top frame). Frame indices change after a step and expire on resume.
includeScopesNoInclude bounded variables from the selected call frame (default: true). Set false when only the stack and source locations are needed.
maxScopeDepthNoScope categories to include for frameIndex (default: 2): 1 reads arguments/locals, 2 also reads closures, and 3+ includes other non-global scopes. Increase only when the needed value is absent.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNo
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.9/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description is fully consistent with them. Beyond that it discloses non-obvious behavioral traits: returned frameIndex values and callFrameIds are valid only for the current pause and expire after any step or resume, which is exactly the kind of statefulness an agent cannot infer from annotations or schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences, front-loaded with what the tool returns, then the negative boundary, then the expiry caveat and next step. No sentence restates the name or repeats schema content verbatim.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Output schema exists, so return shape needn't be explained; annotations cover the safety profile; schema covers all parameters. What remains for the description — pause state dependency, ephemeral handles, and the escape hatch to evaluate_script — is all present.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so all three parameters are documented in structured fields and the baseline is 3. The description adds real value by tying frameIndex to the pause lifecycle (expires on step/resume) and by pointing at evaluate_script as the consumer of that index; includeScopes and maxScopeDepth are left to the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (inspects) plus three concrete resources (call stack, source locations, call-frame scopes) and the precondition that execution is already paused. It also explicitly negates the two adjacent capabilities (creating a pause, resuming), which separates it from pause_or_resume and step without the agent needing to inspect schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives the trigger condition (after a code/XHR breakpoint or explicit pause), the two things it does not do, and a concrete follow-on path: use evaluate_script with frameIndex for an expression, then step or pause_or_resume(action="resume"). Alternatives are named explicitly rather than implied.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

get_request_initiatorA
Read-only

Non-pausing first action for tracing which JavaScript initiated a retained HTTP request when CDP initiator evidence was active. Pass the reqid from list_network_requests; because initiator capture starts lazily and is not retroactive, an older request may have no stack—in that case reproduce the action and inspect the new reqid, or set break_on_xhr before reproduction when runtime values are required. If the captured stack identifies the code, inspect its URL/location with get_script_source. If arguments, locals, or a dynamically built payload are still needed, use break_on_xhr, reproduce, then call get_paused_info or evaluate_script before stepping or resuming. This tool only reads retained evidence and does not pause or reproduce the request.

NameRequiredDescriptionDefault
requestIdYesNumeric reqid returned by list_network_requests, not a raw CDP request ID. It survives navigation while retained, but becomes stale after FIFO eviction or clear_network_requests; list requests again if needed.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNoMachine-readable result payload.
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.6/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already mark as read-only and non-destructive. Description adds key behavioral details: non-pausing, reads retained evidence, initiator capture is lazy and not retroactive. No contradiction.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Single paragraph that is front-loaded with purpose and then flows into usage and alternatives. Every sentence is informative, though slightly dense; could be restructured but remains efficient.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's complexity and the presence of annotations and output schema, the description covers all contextual aspects: limitations, reproduction strategies, and references to sibling tools. Complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema covers requestId fully with description. Tool description adds operational context: pass reqid from list_network_requests, notes on staleness and reproducibility. Provides value beyond schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Clearly states it retrieves the JavaScript initiator for a retained HTTP request, with a specific verb and resource. Distinguishes from siblings by mentioning alternatives like get_script_source, break_on_xhr.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides explicit when-to-use (pass reqid from list_network_requests), when-not-to-use (older request may have no stack), and alternatives (reproduce, set break_on_xhr, use get_paused_info, evaluate_script).

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

get_script_sourceA
Read-only

Reads a small source region around a search match, paused location, or known statement without executing or pausing the page. Select by URL when available because URL-backed scripts can be resolved again after navigation; use the debugger-context-scoped scriptId only for current inline/eval scripts. Use line ranges for normal source and offset/length for minified single-line bundles. For a whole, minified, or WASM source, use save_script_source; to observe runtime values next, call set_breakpoint_on_text against the original loaded source.

NameRequiredDescriptionDefault
urlNoURL from list_scripts, search_in_sources, or a call stack. Preferred stable selector for URL-backed scripts; resolution tries an exact match before a substring match, so provide enough of the URL to avoid ambiguity.
lengthNoMaximum characters to return from offset (default: 1000). This is ignored unless offset is provided.
offsetNoZero-based character offset into the original source. Use for a bounded read of minified single-line code when line ranges would be too large.
endLineNoInclusive 1-based end line for a bounded multi-line snippet. Omit both line bounds and use offset/length for a minified single-line bundle.
scriptIdNoDebugger-context-scoped script ID from list_scripts, search_in_sources, or paused information. Required for unnamed inline/eval scripts, but invalid after reload, navigation, or debugger target/frame change; prefer url for external scripts.
startLineNoInclusive 1-based start line, typically copied from search_in_sources or paused information. Use with endLine for normal multi-line source.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNoMachine-readable result payload.
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.8/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds that it doesn't execute or pause the page, and discloses that scriptId is invalid after reload/navigation. This provides critical behavioral context beyond the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is front-loaded with purpose and core guidance. It is slightly verbose but each sentence serves a distinct instructional purpose. Could be tightened, but remains efficient for the complexity.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Despite 6 parameters and many sibling tools, the description covers selection strategies (URL vs scriptId), parameter combinations (line ranges vs offset/length), edge cases (scriptId invalidation, default length), and explicit alternatives (save_script_source, set_breakpoint_on_text). The output schema exists, so return values are not needed in the description.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the schema documents all 6 parameters. However, the description adds meaningful usage guidance: 'preferred stable selector' for url, 'ignored unless offset is provided' for length, 'for minified single-line code' for offset, 'inclusive 1-based' for lines, and invalidation conditions for scriptId. This enriches the schema without redundancy.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description starts with a specific verb ('Reads') and resource ('small source region'), and immediately clarifies scope ('around a search match, paused location, or known statement') and what it does not do ('without executing or pausing the page'). It also distinguishes from sibling tools like save_script_source and set_breakpoint_on_text.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly advises when to use URL vs scriptId ('prefer URL for external scripts'), when to use line ranges vs offset/length ('normal source' vs 'minified single-line bundles'), and provides alternatives for whole/minified/WASM source ('use save_script_source') and for runtime values ('call set_breakpoint_on_text'). Also explains when scriptId becomes invalid.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

get_websocket_messagesA
Read-only

Inspect captured bidirectional WebSocket connections and frame payloads for the selected page. Use this for WebSocket, socket, live-update, push, streaming, or realtime message flows; use list_network_requests for ordinary HTTP/XHR/fetch traffic and WebSocket upgrade request headers. WebSocket capture starts lazily on this tool's first use and is not retroactive: if the relevant socket already connected or exchanged frames, call this tool once to initialize capture, then reload or reproduce the flow. Without wsid it lists connections so you can choose one. With wsid it lists paginated sent/received frames; add show_content=true for payload previews. With wsid and analyze=true it groups frames by payload pattern and returns group IDs and sample frame indices; then use groupId to inspect one pattern. With wsid and frameIndex it returns one retained frame's detailed payload using the stable index shown in frame tables or analysis samples.

NameRequiredDescriptionDefault
wsidNoSelect a WebSocket connection by the wsid returned from connection-list mode. Omit it to list captured connections before inspecting their frames.
analyzeNoWith wsid, group retained frames by payload pattern/fingerprint. Use this to discover message types in noisy realtime traffic; it returns traffic statistics, group IDs, and sample stable frame indices. Follow with groupId or frameIndex for focused inspection.
groupIdNoWith wsid, list only frames from a pattern group such as A, B, or C. Run analyze=true first to discover group IDs. If analysis used direction, repeat the same direction because grouping is computed over that filtered frame set.
pageIdxNoZero-based page for the active connection-list, frame-list, group-list, or analysis-group mode. Omit it for the first page.
pageSizeNoItems per page: connections when wsid is omitted, frames in normal/group mode, or pattern groups when analyze=true. Defaults to 10.
directionNoWith wsid, restrict frame-list, analysis, or group results to frames "sent" by the page or "received" from the server. It does not filter connection-list mode.
urlFilterNoIn connection-list mode only (without wsid), return WebSocket URLs containing this substring. Use it to narrow by host, path, or query text.
frameIndexNoWith wsid, return one retained frame and its payload by stable frame index. This is the Idx shown in frame tables or analyze=true samples, not a page-relative array offset. Indices are monotonic and may begin above 0 after older frames are evicted.
show_contentNoWith wsid in normal or group frame-list mode, include payload previews up to 10,000 characters for frames on the current page. Leave false for compact metadata, or use frameIndex when one exact frame needs detailed inspection.
includePreservedConnectionsNoIn connection-list mode only (without wsid), include connections preserved from the last three navigations. Use this when the relevant socket belonged to a previous page state.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNo
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.9/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond readOnlyHint and destructiveHint annotations, the description discloses key behaviors: lazy capture start, non‑retroactivity, stable frame indices, monotonic but non‑zero starting indices, and eviction of old frames. This adds substantial value over annotations alone.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single dense paragraph covering all modes and behaviours. While efficient, it could benefit from breaking into bullet points or sections for easier scanning. Still, it earns its place with no redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 10 parameters, multiple modes, and the existence of an output schema, the description is fully complete. It covers initialisation, pagination, filtering, analysis mode, frame indices, and preservation of connections across navigations. No gaps remain.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, but the description adds operational meaning: explaining mode combinations (e.g., without wsid lists connections, with wsid lists frames, with analyze=true groups frames). Clarifies that frameIndex is stable, not page‑relative, and that direction filters but does not apply in connection‑list mode.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool inspects captured bidirectional WebSocket connections and frame payloads. It names the resource (WebSocket messages) and accurately contrasts with sibling tool list_network_requests for ordinary HTTP traffic.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides explicit when to use (WebSocket, socket, live-update, etc.) and when not (use list_network_requests for HTTP/XHR/fetch). Details initialisation caveat (lazy capture, not retroactive) and mode switching between connection listing and frame inspection.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

list_breakpointsA
Read-only

Inspects code and XHR/Fetch breakpoints managed by this MCP session before reproducing an action or cleaning up debugger state. Returns current code breakpointIds and the exact XHR URL patterns needed by remove_breakpoint; URL-backed definitions are restored after navigation when possible, but a rebuilt debugger session may assign new IDs. This does not show why or where execution is currently paused—use get_paused_info for the active call stack.

NameRequiredDescriptionDefault
pageIdxNoPage number (0-based). Defaults to 0.
pageSizeNoMaximum items per page. Defaults to 20.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNo
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.7/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations show readOnlyHint=true and destructiveHint=false. Description adds that URL-backed definitions may restore after navigation but IDs may change in rebuilt sessions, and that it returns breakpointIds and XHR patterns. No contradiction.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Description is concise with three sentences, front-loaded with main purpose. No unnecessary words.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Has output schema, so return details are covered. Description provides enough behavioral context for breakpoint inspection and restoration, given tool complexity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so baseline 3. Description does not add extra meaning beyond schema for pageIdx and pageSize parameters.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool inspects code and XHR/Fetch breakpoints managed by the session. It uses specific verbs and resource, distinguishing itself from siblings like get_paused_info and remove_breakpoint.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly tells when to use this tool: before reproducing an action or cleaning up debugger state. Also directs to use get_paused_info for active call stack, providing clear alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

list_console_messagesA
Read-only

Inspects console messages and uncaught page errors captured for the selected page. Use it to diagnose runtime failures, warnings, application logs, or values already emitted by page code; use search_in_sources for source text and list_network_requests for HTTP evidence instead. Without msgid it lists messages 20 per page by default, optionally filtered by type or retained navigation history. With msgid it returns one message by its stable ID for focused inspection. Capture begins when this MCP attaches and is not retroactive, so reload or reproduce code that logged before attachment.

NameRequiredDescriptionDefault
msgidNoStable message ID returned by list mode. Pass it to inspect one captured console message; omit it to list messages.
typesNoConsole levels/types to include in list mode, such as error, warn, log, or trace. Values are OR-ed; omit or pass an empty array for all types.
pageIdxNoPage number to return (0-based). When omitted, returns the first page.
pageSizeNoMaximum number of messages to return. Defaults to 20.
includePreservedMessagesNoInclude retained console messages from the last 3 navigations. Leave false when only the current page load is relevant.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNo
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.9/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond annotations (readOnlyHint, destructiveHint), description adds critical non-obvious behavior: capture starts on attachment and is not retroactive. No contradiction.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Concise 4-sentence description with front-loaded purpose and alternatives, then clear parameter and behavior details. No unnecessary words.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 5 parameters, output schema, and sibling tools, the description covers all essential aspects: modes, filtering, pagination, capture timing. Complete enough for an agent.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so description adds value by explaining the dual modes (list vs single message), default page size, and optional filters. Slightly above baseline.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Clearly states the tool inspects console messages and uncaught page errors, with specific verb and resource. Differentiates from siblings by naming alternatives search_in_sources and list_network_requests.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly tells when to use (diagnose runtime failures, logs, etc.) and when not to (use other tools for source or network). Also describes modes and parameters affecting usage.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

list_network_requestsA

Inspect captured HTTP(S) traffic for the currently selected page. Use this for API calls, request or response headers and bodies, redirects, authentication/session flows, replay or signing inputs, and determining which response created, refreshed, rotated, overwritten, or deleted a cookie. Without reqid it lists and filters requests; with cookieName it traces exact response Set-Cookie updates oldest-first, including cookies with HttpOnly, Secure, or SameSite attributes that page JavaScript cannot fully inspect; with reqid it returns bounded request details; with reqid plus outputFile it exports exact data. To inspect complete Set-Cookie values and attributes, export outputPart="responseHeaders" for a reqid returned by cookieName mode. cookieName never searches outbound Cookie request headers. Use get_websocket_messages for WebSocket frame payloads; this tool only represents the HTTP upgrade request. Capture begins when this MCP attaches and is not retroactive, so reload or reproduce traffic that occurred earlier. Captures then survive navigation in a 5000-request FIFO queue. List and cookie-flow modes default to 20 items per page; filters combine with AND and multiple values inside one filter combine with OR.

NameRequiredDescriptionDefault
reqidNoInspect one captured request by the reqid returned by request-list or cookie-flow mode. Omit it to list/filter requests or trace cookie setters. Add outputFile when exact, complete, or large data is needed.
methodsNoFilter requests by HTTP method (the request verb). Matched case-insensitively. Pass one or more of GET, POST, PUT, DELETE, PATCH, HEAD, OPTIONS; multiple values are OR-ed (e.g. ["POST"] shows only POSTs, ["GET","POST"] shows both). Use this to hunt for submissions (POST/PUT/PATCH) versus reads (GET). This is the HTTP verb, distinct from resourceTypes which filters by resource category (xhr, document, ...). When omitted or empty, methods are not filtered.
pageIdxNoZero-based page to return in request-list or cookie-flow mode. Omit it for the first page.
pageSizeNoMaximum requests or Set-Cookie updates per page in list or cookie-flow mode. Defaults to 20.
urlFilterNoFilter request-list results to URLs containing this substring. Use an endpoint path, host, query fragment, or other known URL text; combine with methods/resourceTypes to narrow an API flow.
cookieNameNoTrace an exact cookie name in response Set-Cookie headers. Use this when asked where, when, or by which response a cookie was created, refreshed, rotated, overwritten, or deleted, including HttpOnly cookies and cookies carrying Secure or SameSite attributes. Matching setter responses are returned oldest-first with reqids and use pageSize/pageIdx. Export outputPart="responseHeaders" for a returned reqid to inspect the complete value and Path, Domain, HttpOnly, Secure, SameSite, Expires, or Max-Age attributes. This mode does not search outbound Cookie request headers.
outputFileNoWith reqid, save selected network data to a local file. Use export instead of bounded inline details for complete Set-Cookie headers, exact bytes, large or binary bodies, long query payloads, replay/signature inputs, or external decoding. Absolute paths and paths relative to the current working directory are supported. The response reports the resolved absolute path; use it with evaluate_script localFilePath for browser-side processing. Subject to --allowedRoots when configured.
outputPartNoSelect what outputFile receives for the chosen reqid. Use "responseHeaders" for complete cookie attributes and repeated Set-Cookie headers, "responseBody" for raw response bytes, "requestBody" for captured request bytes, "queryParams" for parsed URL parameters, or "all" for a JSON bundle of metadata, headers, query parameters, and body content/metadata. Defaults to "all".all
resourceTypesNoFilter requests to only return requests of the specified resource types (xhr, fetch, document, script, ...). This is the resource category, NOT the HTTP verb — use methods for GET/POST filtering. When omitted or empty, returns all requests.
confirmOverwriteNoMust be true when outputFile already exists. New files do not require confirmation.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNo
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.8/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations are readOnlyHint=false, destructiveHint=false. The description adds rich behavioral context: capture starts on attach, not retroactive, survives navigation with 5000-request FIFO, filter logic, default pagination, cookieName limitations. No contradictions. Provides details beyond annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is long but well-structured with front-loaded purpose. Every sentence adds value, covering many modes and details. However, it is dense and could be slightly streamlined for a quick read, but given the complexity, it remains efficient.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 10 parameters, multiple modes, output schema exists, the description is exceptionally complete. It addresses capture behavior, filter logic, pagination, export options, cookie tracing details, and limitations. No significant gaps.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% so baseline is 3. The description adds extra meaning by explaining parameter interplay (e.g., cookieName + reqid flow, outputFile usage, pageSize default, filter AND/OR). Goes beyond schema by clarifying usage scenarios and combinations, but doesn't introduce entirely new semantics.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states it inspects captured HTTP(S) traffic for the currently selected page, listing specific use cases like API calls, headers, auth flows, cookie tracing. It distinguishes from siblings by explicitly mentioning 'Use get_websocket_messages for WebSocket frame payloads; this tool only represents the HTTP upgrade request.' This provides a specific verb and resource, well differentiated.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Extensive usage guidance is provided: when to use cookieName vs reqid, when to export, default page sizes, AND/OR logic, non-retroactive capture, FIFO queue, and explicit alternative tool mention for WebSockets. Clear context for when and when not to use this tool.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

list_scriptsA
Read-only

Discovers JavaScript currently loaded in the selected debugger context—the main frame by default, or the frame chosen with select_frame. Use select_frame first for iframe-specific source/debugger work. Includes external, inline, and eval scripts in that context; if you already know a function name, endpoint, or code literal, use search_in_sources instead. Each result includes a context-scoped scriptId that expires on reload, navigation, or debugger target change and, for external scripts, a URL that is the preferred selector for get_script_source or save_script_source.

NameRequiredDescriptionDefault
filterNoCase-insensitive URL substring used to narrow external scripts. It does not search source text or match unnamed inline/eval scripts; use search_in_sources for code-content queries.
pageIdxNoPage number (0-based). Defaults to 0.
pageSizeNoMaximum items per page. Defaults to 20.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNo
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.6/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover the read-only safety profile, and the description adds substantially beyond them: context scoping, inclusion of external/inline/eval scripts, and the crucial lifecycle fact that scriptId expires on reload, navigation, or target change. It also recommends URL as the preferred stable selector for downstream calls.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core action, then alternatives, then result semantics. Dense and mostly waste-free, though the final sentence is long and packs several ideas (scriptId lifecycle, URL preference) that could be split for faster scanning.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Output schema exists, yet the description still usefully summarizes what each result contains (context-scoped scriptId, external URL) and warns about expiry. Nothing needed to invoke correctly or to pick the right follow-up tool is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already explains filter as a case-insensitive URL substring and the paging params. The description adds only indirect guidance about external vs inline/eval scripts, leaving the baseline 3 appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ("Discovers JavaScript currently loaded in the selected debugger context") plus the default scope (main frame) and the exception (frame chosen with select_frame). Clearly separable from siblings like search_in_sources and get_script_source.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives explicit routing rules: call select_frame first for iframe-specific work, and use search_in_sources instead when a function name, endpoint, or code literal is already known. Both the when and the when-not are named with concrete triggers.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

new_pageA

Opens a separate browser page for a URL, reusing an existing about:blank startup tab when available. Use this when the task needs another tab or should preserve the currently selected page; use navigate_page to change the URL in the existing selected page instead. It waits for DOMContentLoaded, not every background resource, and then makes the opened page the target for later tools. It preserves cookies, storage, cache, and other browser state; use clear_site_data separately when a clean replay is required.

NameRequiredDescriptionDefault
urlYesAbsolute URL to load in a separate or reusable blank page. Use navigate_page instead when the current selected page should be reused.
timeoutNoMaximum wait time in milliseconds. If set to 0, the default timeout will be used.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNoMachine-readable result payload.
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.9/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description goes beyond annotations (readOnlyHint: false, destructiveHint: false) by detailing behavioral traits: it waits for DOMContentLoaded (not every resource), makes the opened page the target for later tools, and preserves cookies/storage/cache. It also mentions using clear_site_data separately for a clean replay. No contradictions with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is four sentences, well-structured: first sentence states the main action, second provides usage guidance, third adds behavioral details, fourth mentions state preservation. No redundant or unnecessary information; every sentence earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the output schema exists and parameters are fully described in the schema, the description provides sufficient context: what the tool does, when to use it, behavioral characteristics, and contrast with sibling. It is complete for the tool's complexity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so baseline is 3. The description adds value by explaining the context of the url parameter (absolute URL, reusing about:blank tab), which is not fully captured in the schema's description. However, the timeout parameter is not elaborated beyond the schema, so not a perfect 5.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states that the tool opens a separate browser page for a URL, reusing an existing about:blank startup tab. It distinguishes itself from the sibling navigate_page by specifying that navigate_page changes the URL in the existing selected page, making the purpose specific and well-differentiated.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

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 (when the task needs another tab or should preserve the currently selected page) and when to use the alternative (navigate_page to change the URL in the existing selected page). This provides clear guidelines for tool selection.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

pause_or_resumeA

Explicitly requests an immediate pause or resumes an existing paused execution; it never toggles implicitly. Use a code breakpoint or break_on_xhr instead when a specific statement/request should stop, and use get_paused_info before resuming if evidence must be collected. Resuming invalidates current callFrameIds and frame indices.

NameRequiredDescriptionDefault
actionYesUse "pause" only while running, or "resume" only after a breakpoint/manual pause. Resume after get_paused_info/evaluate_script/step inspection is complete.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNoMachine-readable result payload.
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.7/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Discloses state-changing behavior and invalidation side effect. While annotations are limited, description adds useful context beyond them. Could be improved by noting error scenarios.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Concise, front-loaded with main purpose, then alternatives and side effects. No redundant sentences.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Complete for a simple tool: single parameter fully described, usage prerequisites, side effect noted. Given schema coverage and output schema presence, further detail unnecessary.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema covers enum with descriptions; description adds valuable usage tips (when to use each value, ordering) that go beyond schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Clearly states it pauses or resumes execution explicitly, never toggles. Contrasts with break_on_xhr and step, providing clear purpose.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly describes when to use alternatives (break_on_xhr, get_paused_info) and warns that resuming invalidates callFrameId, offering clear guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

remove_breakpointA
DestructiveIdempotent

Removes a known code breakpoint, XHR/Fetch breakpoint, or every MCP-managed breakpoint after explicit confirmation. Use breakpointId from set_breakpoint_on_text/list_breakpoints for remove_code, or reuse the exact URL pattern from break_on_xhr/list_breakpoints for remove_xhr. Removal does not resume an already paused page; call pause_or_resume(action="resume") separately after inspection.

NameRequiredDescriptionDefault
urlNoExact URL substring pattern previously passed to break_on_xhr or returned by list_breakpoints. Used only with action="remove_xhr".
actionYesRequired removal mode: remove_code needs breakpointId, remove_xhr needs url, and remove_all removes both kinds.
confirmNoMust be true to authorize the selected removal action. This does not authorize or trigger resuming execution.
breakpointIdNoCurrent breakpoint ID returned by set_breakpoint_on_text or list_breakpoints. Used only with action="remove_code"; list again after a debugger/page-session rebuild because restoration may assign a new ID.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNoMachine-readable result payload.
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A5/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description discloses that removal does not resume a paused page, requires confirmation, and that breakpointId may need to be re-obtained after a debugger rebuild. This adds context beyond annotations (destructiveHint, idempotentHint, readOnlyHint) without contradiction.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences that are front-loaded with the primary action and then provide usage specifics. No redundant or extraneous information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool has 4 parameters, 1 required, and an output schema, the description covers all essential aspects: removal modes, parameter usage, confirmation requirement, post-removal behavior, and edge case handling (breakpointId rebuild). Complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Despite 100% schema coverage, the description adds meaning to each parameter: explains url as an exact substring pattern, breakpointId caveat about session rebuild, confirm's authorization role, and action enum values. This enhances understanding beyond the schema's brief descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description specifies the verb 'removes' and the resource 'breakpoint' with three distinct removal modes (code, XHR, all). It references sibling tools (set_breakpoint_on_text, break_on_xhr, list_breakpoints, pause_or_resume) to differentiate when each mode is applicable.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicit guidance on when to use each action: use breakpointId from set_breakpoint_on_text/list_breakpoints for remove_code, use exact URL pattern from break_on_xhr/list_breakpoints for remove_xhr. Also clarifies that removal does not resume a paused page and suggests calling pause_or_resume separately.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

save_script_sourceA

Saves one complete JavaScript or WASM source for local inspection when an inline snippet is insufficient, especially for large or minified bundles. Prefer get_script_source for a small known region and search_in_sources to locate text across loaded scripts first. With format=true, destinations using a supported JavaScript/TypeScript extension are formatted by default; other extensions preserve raw source, and formatted line numbers may differ from the live page. Use distinctive text plus the original URL with set_breakpoint_on_text for runtime debugging. The returned filename is the resolved local path, while scriptId remains scoped to the current debugger context.

NameRequiredDescriptionDefault
urlNoURL from list_scripts, search_in_sources, or a call stack. Preferred over scriptId because it can be resolved again after navigation; exact match is tried before substring match.
formatNoFormat supported JavaScript/TypeScript extensions for readability (default: true). Set false when exact source bytes or original line layout matter; formatted line numbers cannot be used as live breakpoint locations.
filePathYesDestination path for the complete source, absolute or relative to the server working directory and subject to --allowedRoots. A JavaScript/TypeScript extension enables formatting; use .wasm for bytecode or another extension to preserve raw text.
scriptIdNoDebugger-context-scoped script ID from list_scripts or search_in_sources. Use for unnamed inline/eval scripts; it becomes invalid after reload, navigation, or debugger target/frame change.
confirmOverwriteNoSet true only to authorize replacing an existing filePath. A new file does not require overwrite confirmation.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNoMachine-readable result payload.
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.7/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description discloses key behaviors: formatted line numbers may differ from live page, filePath is the resolved local path, and scriptId is scoped to current debugger context and becomes invalid after navigation/refresh. Annotations show readOnlyHint=false and destructiveHint=false, which are consistent. One minor gap: it doesn't mention that the saved file persists or any access restrictions beyond --allowedRoots.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is detailed but every sentence is informative. It is front-loaded with the main purpose. While slightly long, it avoids redundancy. Could be trimmed slightly, but overall effective.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 5 parameters with rich schema, output schema present, the description covers purpose, sibling differentiation, behavioral nuances, and parameter semantics. It mentions the returned filename implicitly. No obvious gaps for the tool's complexity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, but the description adds significant context for each parameter. For url, it explains preferred source and matching strategy. format is described with clear use cases. filePath explains extension implications. scriptId clarifies scoping and invalidation. confirmOverwrite notes authorization. This goes well beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states that the tool saves a complete JavaScript or WASM source for local inspection when an inline snippet is insufficient. It differentiates from siblings by mentioning 'Prefer get_script_source for a small known region and search_in_sources to locate text across loaded scripts first.' The specific verb 'saves' and resource 'source' make purpose unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicit usage guidance is provided: prefer get_script_source for small regions, use search_in_sources first, and use set_breakpoint_on_text for debugging. It also clarifies when to set format=false and when to use confirmOverwrite. This helps the agent decide when to invoke this tool over its siblings.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

search_in_sourcesA
Read-only

Finds a known function name, endpoint, string literal, token, or code pattern in JavaScript loaded by the selected debugger context—the main frame by default, or the frame chosen with select_frame. It searches external, inline/eval, and minified sources in that context without executing or pausing the page, returning 1-based lines plus context-scoped scriptIds; URLs are the preferred selectors for URL-backed matches. Use select_frame first for iframe-specific source work, get_script_source for nearby context, save_script_source for a whole bundle, or set_breakpoint_on_text when runtime values are needed. For a known captured request, prefer get_request_initiator before a broad source search.

NameRequiredDescriptionDefault
queryYesSource text to locate, or a regular-expression pattern when isRegex=true. Prefer a distinctive function name, endpoint, property, or literal that can also anchor set_breakpoint_on_text.
isRegexNoInterpret query as a regular expression when true. Leave false for literal endpoint, token, and code-text searches.
urlFilterNoCase-insensitive script-URL substring used to narrow matches to a known bundle or domain. It excludes unnamed inline/eval scripts.
maxResultsNoMaximum matches to return (default: 30). Narrow with urlFilter before increasing this for common text.
caseSensitiveNoMatch case exactly when true. Leave false for discovery; set true when choosing exact code text for a breakpoint.
maxLineLengthNoMaximum characters in each matched-line preview (default: 150). Use get_script_source rather than a very large preview when surrounding context is needed.
excludeMinifiedNoSkip sources with very long lines when true. Keep the default false for reverse engineering because relevant code often exists only in compressed bundles.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNo
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.7/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations declare readOnlyHint and destructiveHint false, but the description adds important behavior beyond that: it searches without executing or pausing the page, covers external, inline/eval, and minified sources, and returns 1-based lines plus context-scoped scriptIds. It also notes that URLs are preferred selectors for URL-backed matches.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The purpose is front-loaded in the first sentence, and the second sentence efficiently covers behavior, return shape, and alternatives. Although dense, every clause adds actionable information for selecting and invoking the tool.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The definition is complete for a search tool with seven well-described parameters, read-only annotations, and an output schema. It covers scope, alternatives, source types, and non-execution behavior without needing to restate return-value structure that the output schema already defines.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the detailed parameter descriptions already carry most semantic weight. The main description adds some strategic guidance, such as preferring URLs for URL-backed matches, but does not explain the roles of maxResults, caseSensitive, maxLineLength, or excludeMinified beyond what the schema provides.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource: finding known function names, endpoints, literals, tokens, or code patterns in JavaScript sources loaded by the selected debugger context. It clearly scopes the search to the main frame by default or the frame chosen with select_frame, and distinguishes itself from sibling tools by naming alternatives.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly routes the agent: use select_frame for iframe-specific work, get_script_source for nearby context, save_script_source for whole bundles, set_breakpoint_on_text when runtime values are needed, and get_request_initiator for known captured requests. These are concrete when-to-use and when-to-use-alternative instructions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

select_frameA

Lists or selects frames, including iframes, within the current page. Use it when the target element, page-defined global, script, or execution context may live in an iframe: first list frames, then pass frameIdx before click_element or evaluate_script. Omitting frameIdx lists 20 frames per page without changing context; passing frameIdx changes the shared frame target, with 0 restoring the main frame. It does not switch browser tabs or navigate—use select_page or navigate_page for those actions—and listPageIdx only paginates this listing.

NameRequiredDescriptionDefault
frameIdxNoFrame index from the latest frame listing. Pass it to target later frame-aware tools; 0 restores the main frame. Omit it to list frames without changing context, and re-list after navigation or frame attachment/detachment because indices can shift.
pageSizeNoMaximum frames to list per response. Defaults to 20.
listPageIdxNoZero-based pagination index for the frame listing only. This is not the frameIdx used to select a frame. Defaults to 0.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNo
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.7/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Discloses behavioral traits beyond annotations: omitting frameIdx lists without changing context; passing frameIdx changes target; indices shift after navigation or frame changes. No contradiction with readOnlyHint=false (mutates state) and destructiveHint=false.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Single dense paragraph front-loads purpose, then usage, then behavior, then exclusions. Each sentence adds value; no fluff.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the complexity (3 params, output schema), the description covers purpose, workflow, side effects, and exclusions. It references sibling tools for related actions.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so baseline is 3. The description adds workflow context but does not significantly expand parameter meaning beyond what the schema provides.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states 'Lists or selects frames, including iframes, within the current page.' It specifies the verb (lists or selects) and resource (frames within current page), and distinguishes from siblings like select_page and navigate_page.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly tells when to use: 'when the target element... may live in an iframe' and provides a workflow: first list frames, then pass frameIdx before click_element or evaluate_script. Also tells when not to use: 'It does not switch browser tabs or navigate—use select_page or navigate_page for those actions.'

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

select_pageA

Lists or selects open browser pages. Use it without pageIdx to identify the active page or choose the correct tab before inspecting network traffic, scripts, frames, or console output; pass pageIdx to make one listed page the shared target for later tools. It does not navigate or create pages: use navigate_page to change the selected page's URL and new_page when a separate tab is required. listPageIdx only paginates the page listing and never changes selection.

NameRequiredDescriptionDefault
pageIdxNoSnapshot index from the latest page listing. Pass it to make that page the target for later tools; omit it to list pages without changing selection. Re-list after pages open or close because indices can shift.
pageSizeNoMaximum pages to list per response. Defaults to 20.
listPageIdxNoZero-based pagination index for the page listing only. This is not the pageIdx used to select a browser page. Defaults to 0.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNo
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.9/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description explains the behavioral nuance: listing does not change selection, passing pageIdx makes it the target. This adds value beyond the annotations, which only indicate non-destructive behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences, no fluff, front-loaded with the core purpose. Every sentence adds necessary detail without redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the complexity of selection and pagination, the description is complete. It covers all key behaviors and constraints, and an output schema exists so return values need not be detailed.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% with good descriptions, but the tool description adds context about how each parameter affects behavior (e.g., pageIdx changes selection, listPageIdx only paginates). This enhances understanding.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool lists or selects open browser pages, with a specific verb and resource. It distinguishes from sibling tools like navigate_page and new_page by stating what it does not do.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly tells when to use without pageIdx vs with pageIdx, and provides alternatives (navigate_page, new_page). It also clarifies that listPageIdx only paginates and never changes selection.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

set_breakpoint_on_textA

Sets a restorable URL-backed breakpoint when distinctive code text is known and its runtime values must be observed. Call it directly when the user already supplies precise text plus any URL/occurrence disambiguation; use search_in_sources/get_script_source first only when the location is unknown or ambiguous. For an API with no known code location, start with list_network_requests and get_request_initiator or use break_on_xhr. On a hit, call get_paused_info, optionally evaluate_script, then step or resume. Returns the current breakpointId for remove_breakpoint; list breakpoints again after a rebuilt debugger session, and note that unnamed inline/eval scripts cannot use this URL breakpoint.

NameRequiredDescriptionDefault
textYesExact case-sensitive source text used to locate the breakpoint, such as a distinctive function declaration, call, or statement. Prefer a snippet confirmed by search_in_sources and avoid common tokens.
conditionNoOptional simple synchronous expression evaluated in the future call frame; the breakpoint pauses only when it is true. Use it to reduce repeated hits after the location is precise, never for async work, complex discovery, or side effects.
urlFilterNoCase-insensitive URL substring that limits candidate scripts. Use the URL from search_in_sources/get_script_source to avoid the same text in unrelated bundles.
occurrenceNoOne-based occurrence among matching loaded-source results (default: 1). Use only after reviewing multiple search matches; urlFilter is usually the more stable disambiguator.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNoMachine-readable result payload.
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.9/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Adds context beyond annotations: restorable, returns breakpointId, limitation for inline/eval scripts.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Dense single paragraph, front-loads purpose, but could be slightly more structured for readability.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Covers purpose, usage, workflow, return value, and limitations; output schema covers return details.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Adds valuable guidance for each parameter (e.g., prefer confirmed snippet, condition restrictions, urlFilter source, occurrence usage).

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Clearly states it sets a URL-backed breakpoint on text, distinguishes from siblings like search_in_sources, break_on_xhr.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly states when to call directly vs. use alternatives (search_in_sources, break_on_xhr) and provides workflow after hit.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

stepA

Advances JavaScript execution by one debugger operation from an existing pause and returns the next stopped call frame with concise source context. Use after get_paused_info or evaluate_script when control flow still needs tracing; it cannot start from running execution. Each advance invalidates prior callFrameIds, so inspect the new pause again as needed, then use pause_or_resume(action="resume") to finish.

NameRequiredDescriptionDefault
directionYesChoose "over" for the next statement without entering calls, "into" to follow a call, or "out" to continue until the current function returns.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNoMachine-readable result payload.
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.7/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations indicate readOnlyHint=false and destructiveHint=false. The description adds critical behavioral details: invalidates prior callFrameIds, requires existing pause, and returns next call frame. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Description is efficient and front-loaded with the main action. Three sentences cover behavior, prerequisites, and follow-up without fluff. Every sentence adds value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given full parameter schema, annotations, and output schema, the description is complete. It covers prerequisites, invalidation, and next steps, leaving no gaps for an agent.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% with descriptions for the direction parameter. The tool description does not add extra meaning beyond the schema, so baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states it advances JavaScript execution by one debugger operation from a pause, with a specific verb and resource. It distinguishes from siblings like pause_or_resume and get_paused_info by specifying its role in tracing control flow.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly says to use after get_paused_info or evaluate_script when control flow needs tracing, and not from running execution. Also directs to use pause_or_resume to finish, providing clear context and alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

take_screenshotA

Captures the visual state of the currently selected page. Use it to verify page layout, visible UI state, selector targets, in-page dialogs/modals, or the effect of a navigation/click; it is not a substitute for DOM values, network evidence, or script inspection. By default it returns the visible viewport, while fullPage=true captures the whole document; oversized captures may be saved as a temporary artifact instead of attached. Pass filePath for a reusable local artifact; existing files require confirmOverwrite=true and remain subject to --allowedRoots.

NameRequiredDescriptionDefault
formatNoImage format for the attachment or saved file. Defaults to png; use jpeg when smaller lossy output is preferred.png
qualityNoCompression quality for JPEG format (0-100). Higher values mean better quality but larger file sizes. Ignored for PNG format.
filePathNoOptional absolute or working-directory-relative path for a reusable screenshot artifact. Omit it to attach the image directly. Subject to --allowedRoots when configured.
fullPageNoCapture the entire scrollable document when true; leave false or omit it for the currently visible viewport.
confirmOverwriteNoMust be true when filePath already exists. New files do not require confirmation.

Output Schema

NameRequiredDescription
okYesWhether the tool completed successfully.
dataNoMachine-readable result payload.
toolYesStable MCP tool name.
errorNo
summaryYesConcise human-readable outcome.

TDQS

A4.7/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations are minimal (readOnlyHint=false, destructiveHint=false); description adds critical behavioral details: default viewport vs. fullPage, oversized capture handling, filePath behavior and confirmOverwrite requirement, fully disclosing tool behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Concise 4-sentence description, front-loaded with purpose and usage, no repetition or fluff, efficiently communicates all necessary information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 5 optional parameters, full schema documentation, and presence of output schema, the description covers purpose, usage, behavioral nuances, and key parameter implications, making it fully self-contained.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so baseline is 3. Description adds minimal param-specific insight beyond schema (e.g., fullPage behavior, oversized captures), but does not significantly enhance parameter understanding.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Clearly states 'Captures the visual state of the currently selected page.' and distinguishes from sibling tools by specifying it is not a substitute for DOM values, network evidence, or script inspection.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly lists use cases (verify page layout, UI state, etc.) and explicitly states when not to use it (not for DOM, network, or script), providing clear guidance for selection.

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.

  1. 24 tool updatesv4.0.5
    • First observedbreak_on_xhr
    • First observedclear_network_requests
    • First observedclear_site_data
    • First observedclick_element
    • First observedevaluate_script
    • First observedget_paused_info
    • First observedget_request_initiator
    • First observedget_script_source
    • First observedget_websocket_messages
    • First observedlist_breakpoints
    • First observedlist_console_messages
    • First observedlist_network_requests
    • First observedlist_scripts
    • First observednavigate_page
    • First observednew_page
    • First observedpause_or_resume
    • First observedremove_breakpoint
    • First observedsave_script_source
    • First observedsearch_in_sources
    • First observedselect_frame
    • First observedselect_page
    • First observedset_breakpoint_on_text
    • First observedstep
    • First observedtake_screenshot

TDQS

A4.6/5.0

Scored across 24 tools

Disambiguation5/5

Each tool targets a distinct resource+action: network, console, websocket, sources (list/search/get/save), breakpoints (set/list/remove/break_on_xhr), pause control, frame/page selection, and interaction. Descriptions actively route between near-neighbors (e.g. get_script_source vs save_script_source vs search_in_sources, get_request_initiator vs break_on_xhr), so an agent can reliably pick the right one.

Naming Consistency4/5

Consistent snake_case with a dominant verb_noun pattern (list_network_requests, get_script_source, remove_breakpoint, clear_site_data, select_frame). A few deviations — new_page (no verb), break_on_xhr (verb_prep_noun), step and pause_or_resume (bare/compound verbs) — but all remain readable and semantic.

Tool Count4/5

24 tools is on the heavy side, but the domain (CDP-level browser reverse engineering) genuinely spans network, debugger, source, frame, page, and interaction surfaces, and each tool maps to a real capability with no filler. Slightly over a lean set but reasonable for the scope.

Completeness4/5

Coverage of the reverse-engineering core is strong: HTTP and WebSocket evidence, console, source discovery/inspection, code and XHR breakpoints, pause/step, and site/network reset. Gaps exist on the interaction side (no text input/keypress/hover/scroll or wait-for-selector), and breakpoints are text- or URL-based only (no line/column breakpoint), which agents must work around via evaluate_script or click_element.

Maintenance

ActivitySlowing
ResponsivenessNo issues

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