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Charlotte

网页,可读。

你的 AI 代理仅为了查看 Hacker News 首页就要消耗约 50,000 个字符的可访问性树。Charlotte 只需 364 个字符。

Charlotte 是一个 MCP 服务器,为 AI 代理提供结构化、令牌高效的网页访问。它不会在每次调用时转储完整的可访问性树,而是只返回代理所需的内容:到达时的紧凑页面摘要、针对特定元素的定向查询,以及仅在明确请求时才提供的完整细节。在内容密集的页面上,这种定向信息比 Playwright MCP 的完整可访问性树快照小约 140 倍;在极小的页面上,两者大小大致相同。

为什么选择 Charlotte?

大多数浏览器 MCP 服务器在每次调用时都会转储整个可访问性树——一个扁平文本块,在内容密集的页面上可能超过一百万个字符。无论代理是否需要,它都要为所有这些字符付费。

Charlotte 将每个页面分解为类型化、结构化的表示——地标、标题、交互元素、表单、内容摘要——并让代理通过三个详细级别控制接收多少内容。当代理导航到新页面时,它获得的是紧凑的定向信息(Hacker News 为 364 个字符),而不是完整的元素转储(约 50,000 个字符)。当它需要具体信息时,它会主动请求。

基准测试

在 Charlotte v0.8.0 上针对 Playwright MCP v0.0.79 测量,按真实网站上每次工具调用返回的字符数计算(npx tsx benchmarks/run-benchmarks.ts --suite comparison),2026-08-08。本节是摘要——权威基准测试页面(包括每任务成本和发布漂移)位于 charlotte.mintlify.site/benchmarks;方法论、工具和原始结果:benchmarks/

定向成本(代理到达页面时“查看”页面所需支付的费用):

Charlotte 的 navigate 默认返回可用的定向信息——按页面区域分组的地标、标题和交互元素计数。要获得与 Playwright MCP 等效的结果,代理需要调用 browser_snapshot,它会返回完整的可访问性树。(Playwright 的 browser_navigate 单独只返回简短的确认信息,而不是页面内容,因此不是同类比较。)

站点

Charlotte navigate

Playwright browser_snapshot

缩小倍数

example.com

415

465

1.1x

httpbin 表单

619

1,847

3.0x

GitHub 仓库

3,778

38,983

10x

Wikipedia(AI 文章)

22,134

1,137,928

51x

Hacker News

364

50,706

139x

优势随页面复杂度增长:在内容密集的页面上,结构化定向信息比完整快照小 约 10–140 倍,而在像 example.com 这样极小的页面上,两者相差约 20%(在如此小的页面上,结构化表示可能反而更大——因为根本没有可总结的内容)。Charlotte 的价值恰恰体现在 Playwright 的扁平转储最令人头疼的地方。当代理需要超出定向信息的内容时,它会调用 observefind 来精确获取所需部分,而不是预先为整棵树付费。

工具定义开销(每次 API 调用的隐性成本):

配置

工具数

定义令牌/调用

与完整版相比节省

full

43

8,500

browse(默认)

23

4,372

约 49%

core

7

2,186

约 75%

工具定义在每次 API 往返中都会发送。使用默认的 browse 配置,Charlotte 比加载全部 43 个工具少约 49% 的定义开销;最小的 core 配置可减少约 75%。完整结果请参阅 配置基准测试报告

工作流差异: 使用 Playwright 的代理每次查看 Hacker News 时都会收到约 50,000 个字符的完整快照,无论它是在阅读标题还是寻找登录按钮。Charlotte 代理到达时只收到 364 个字符,调用 find({ type: "link", text: "login" }) 来精确获取所需内容,并且永远不必为其余部分付费。

Related MCP server: krwl3r

工作原理

Charlotte 维护一个持久的无头 Chromium 会话,并充当视觉网页与代理的文本原生推理之间的翻译层。每个页面都被分解为结构化表示:

┌─────────────┐     MCP Protocol     ┌──────────────────┐
│   AI Agent  │<────────────────────>│    Charlotte     │
└─────────────┘                      │                  │
                                     │  ┌────────────┐  │
                                     │  │  Renderer  │  │
                                     │  │  Pipeline  │  │
                                     │  └─────┬──────┘  │
                                     │        │         │
                                     │  ┌─────▼──────┐  │
                                     │  │  Headless  │  │
                                     │  │  Chromium  │  │
                                     │  └────────────┘  │
                                     └──────────────────┘

代理接收地标、标题、带类型元数据的交互元素、边界框、表单结构和内容摘要——所有这些都来自浏览器已经了解的每个页面信息。

功能

导航navigatebackforwardreload

观察observe(3 个详细级别,结构树视图)、find(空间 + 语义搜索,CSS 选择器模式,output_file 用于大型结果集)、screenshot(带持久化工件管理)、screenshotsscreenshot_getscreenshot_deletediff(与快照的结构比较)

交互(支持 iframe)— clickclick_at(基于坐标)、type(支持慢速输入)、selecttogglesubmitscrollhoverdragkey(单键/序列,支持元素定位)、wait_for(异步条件轮询)、upload(文件输入)、fill_form(批量表单填写)、dialog(接受/拒绝 JS 对话框)

监控console(所有严重级别,过滤,时间戳)、requests(完整 HTTP 历史,方法/状态/资源类型过滤)

会话管理tabstab_opentab_switchtab_closeviewport(通用预设或命名设备,如“iPhone 15”,支持 DPR、触摸和用户代理模拟)、network(限速、URL 阻止)、set_cookiesget_cookiesclear_cookiesset_headersconfigure

开发模式dev_serve(静态服务器 + 文件监视,自动重载)、dev_inject(CSS/JS 注入)、dev_audit(可访问性、性能、SEO、对比度、损坏链接)

实用工具evaluate(在页面上下文中执行任意 JS)

工具配置

Charlotte 提供 43 个工具(42 个注册工具 + charlotte_tools 元工具),但大多数工作流只需要一个子集。启动配置控制哪些工具加载到代理的上下文中,将定义开销减少多达约 75%。

charlotte --profile browse    # 23 tools (default) — navigate, observe, interact, tabs
charlotte --profile core      # 7 tools — navigate, observe, find, click, type, submit
charlotte --profile full      # 43 tools — everything
charlotte --profile interact  # 31 tools — full interaction + dialog + evaluate
charlotte --profile develop   # 34 tools — interact + dev_serve, dev_inject, dev_audit
charlotte --profile audit     # 14 tools — navigation + observation + dev_audit + viewport

代理可以在会话中途激活更多工具,无需重启:

charlotte_tools enable dev_mode    → activates dev_serve, dev_audit, dev_inject
charlotte_tools disable dev_mode   → deactivates them
charlotte_tools list               → see what's loaded

自托管(Charlotte Remote)

将 Charlotte 作为远程 MCP 服务器运行,并连接到 claude.ai——一条命令:

docker run --cap-add SYS_ADMIN --shm-size 2g -p 3737:3737 ghcr.io/ticktockbent/charlotte

它会打印一个公共连接器 URL 和一个操作员令牌。在 claude.ai 中: 设置 → 连接器 → 添加自定义连接器 — 粘贴 URL,将 OAuth 客户端 ID/密钥字段留空,并在出现时在 Charlotte 的同意 页面上输入令牌。就这样;你就可以浏览了。

演示 URL 和令牌是临时的(两者在重启时都会轮换)。要正式运行—— 稳定的域名、你自己的隧道或反向代理、docker compose: 自托管。信任模型和 网络防护:安全。容器 和沙箱内部:Docker

快速开始

前提条件

  • Node.js >= 20

  • npm

安装

Charlotte 在 MCP 注册表 上以 io.github.TickTockBent/charlotte 列出,并在 npm 上发布为 @ticktockbent/charlotte

npm install -g @ticktockbent/charlotte

Docker 镜像可在 Docker HubGitHub Container Registry 上获取:

# Alpine (default, smaller)
docker pull ticktockbent/charlotte:alpine

# Debian (if you need glibc compatibility)
docker pull ticktockbent/charlotte:debian

# Or from GHCR
docker pull ghcr.io/ticktockbent/charlotte:latest

或者从源码安装:

git clone https://github.com/ticktockbent/charlotte.git
cd charlotte
npm install
npm run build

运行

Charlotte 通过 stdio 使用 MCP 协议通信:

# If installed globally (default browse profile)
charlotte

# With a specific profile
charlotte --profile core

# If installed from source
npm start

MCP 客户端配置

Claude Code

在项目根目录创建 .mcp.json

{
  "mcpServers": {
    "charlotte": {
      "type": "stdio",
      "command": "npx",
      "args": ["@ticktockbent/charlotte"],
      "env": {}
    }
  }
}

Claude Desktop

添加到 claude_desktop_config.json

{
  "mcpServers": {
    "charlotte": {
      "command": "npx",
      "args": ["@ticktockbent/charlotte"]
    }
  }
}

Cursor

添加到 .cursor/mcp.json

{
  "mcpServers": {
    "charlotte": {
      "command": "npx",
      "args": ["@ticktockbent/charlotte"]
    }
  }
}

Windsurf

添加到 ~/.codeium/windsurf/mcp_config.json

{
  "mcpServers": {
    "charlotte": {
      "command": "npx",
      "args": ["@ticktockbent/charlotte"]
    }
  }
}

VS Code(Copilot)

添加到 .vscode/mcp.json

{
  "servers": {
    "charlotte": {
      "type": "stdio",
      "command": "npx",
      "args": ["@ticktockbent/charlotte"]
    }
  }
}

Cline

添加到 Cline MCP 设置(通过 Cline 侧边栏 > MCP 服务器 > 配置):

{
  "mcpServers": {
    "charlotte": {
      "command": "npx",
      "args": ["@ticktockbent/charlotte"]
    }
  }
}

Amp

添加到 ~/.amp/settings.json

{
  "mcpServers": {
    "charlotte": {
      "command": "npx",
      "args": ["@ticktockbent/charlotte"]
    }
  }
}

完整设置指南(包括开发模式、通用 MCP 客户端、验证步骤和故障排除)请参阅 docs-internal/mcp-setup.md

配置

Charlotte 从四个来源解析设置,优先级从高到低:CLI 参数 → 环境变量 → 配置文件 → 内置默认值。完整参考请参阅 docs/configuration.md

配置文件

使用 --config 传入 JSON 配置文件,或将 charlotte.config.json 放在工作目录中,Charlotte 会自动加载:

charlotte --config charlotte.config.json
{
  "browser": { "headless": true, "noSandbox": false },
  "tools": { "profile": "browse" },
  "rendering": { "includeIframes": false, "iframeDepth": 3 },
  "output": { "dir": "./charlotte-output" },
  "limits": {
    "maxInteractiveElements": 2000,
    "maxFullContentChars": 200000,
    "maxResponseBytes": 1000000,
    "maxEvaluateBytes": 256000
  }
}

每个部分都是可选的;空的 {} 也是有效的。文件使用 zod 验证——未知键、错误类型或无效枚举值会在 stderr 上产生清晰的启动错误,Charlotte 以非零状态退出。四个设置也有环境变量:CHARLOTTE_NO_SANDBOXCHARLOTTE_OUTPUT_DIRCHARLOTTE_CDP_ENDPOINTCHARLOTTE_INIT_SCRIPT。应在每个新文档上、页面 JS 之前运行的脚本放在 browser.initScripts--init-script <path>(可重复)中;请参阅 初始化脚本

Chromium 沙箱默认开启

v0.7.0 行为变更: 早期版本在每次 Chromium 启动时都内置了 --no-sandbox。从 v0.7.0 开始,Chromium 沙箱默认启用——这是不受信任的页面与 Charlotte 运行账户之间的主要防线。在无法使用内核沙箱的环境中,你必须明确选择退出。

charlotte --no-sandbox                  # CLI flag
CHARLOTTE_NO_SANDBOX=1 charlotte        # environment variable
# or "browser": { "noSandbox": true }   in the config file

迁移说明(Docker / 裸机): 容器通常无法设置内核沙箱,因此提供的 Dockerfile 会为你设置 CHARLOTTE_NO_SANDBOX=1,并且 docker-compose.yml 现在保留 Docker 默认的 seccomp 过滤器(不再运行 seccomp=unconfined)。如果你以 root 身份在裸机上运行 Charlotte,Chromium 在启用沙箱时会拒绝启动——请以非 root 用户运行(推荐)或传递 --no-sandbox。以前依赖隐式 --no-sandbox 且在沙箱无法初始化的环境中运行的现有设置,现在必须设置 CHARLOTTE_NO_SANDBOX=1(或等效的 flag/配置)才能继续工作。

通过网络运行 Charlotte Remote(HTTP 模式)会引发超出沙箱的额外信任边界和网络防护问题——请参阅 安全

输出大小限制

limits.* 键限制单个工具响应可以返回多少内容,这样病态页面(10 万个链接、无限滚动 feed、巨大的文档主体)就不会溢出代理的上下文窗口。当页面响应超过 maxResponseBytes 时,它会降级为紧凑摘要,并建议通过 output_file 将完整结果写入磁盘;charlotte_evaluate 的结果由 maxEvaluateBytes 独立限制。截断的响应带有 truncation 标记。键和默认值请参阅 docs/configuration.md

崩溃恢复

Chromium 崩溃不再使服务器卡死。下一次工具调用会自动重新启动浏览器,清除死标签页和 CDP 会话缓存,并打开一个新的空白标签页——这样代理在渲染器崩溃后无需重启 MCP 服务器即可继续工作。

使用示例

连接后,代理可以使用 Charlotte 的工具:

浏览网站

navigate({ url: "https://example.com" })
// → 612 chars: landmarks, headings, interactive element counts

find({ type: "link", text: "More information" })
// → just the matching element with its ID

click({ element_id: "lnk-a3f1c2" })

填写表单

navigate({ url: "https://httpbin.org/forms/post" })
find({ type: "text_input" })
type({ element_id: "inp-c7e29b", text: "hello@example.com" })
select({ element_id: "sel-e8a3f5", value: "option-2" })
submit({ form_id: "frm-b1d4e7" })

本地开发反馈循环

dev_serve({ path: "./my-site", watch: true })
observe({ detail: "full" })
dev_audit({ checks: ["a11y", "contrast"] })
dev_inject({ css: "body { font-size: 18px; }" })

页面表示

Charlotte 返回具有三个详细级别的结构化表示,让代理控制它们消耗多少上下文:

最小(navigate 的默认值)

地标、标题和按页面区域分组的交互元素计数。专为定位而设计——“这个页面上有什么?”——而不列出每个元素。

{
  "url": "https://news.ycombinator.com",
  "title": "Hacker News",
  "viewport": { "width": 1280, "height": 720 },
  "structure": {
    "headings": [{ "level": 1, "text": "Hacker News", "id": "hdg-a1b2c3" }]
  },
  "interactive_summary": {
    "total": 93,
    "by_landmark": {
      "(page root)": { "link": 91, "text_input": 1, "button": 1 }
    }
  }
}

摘要(observe 的默认值)

完整的交互元素列表,包含类型化元数据、表单结构和内容摘要。

{
  "url": "https://example.com/dashboard",
  "title": "Dashboard",
  "viewport": { "width": 1280, "height": 720 },
  "structure": {
    "landmarks": [
      { "id": "rgn-b2c1d0", "role": "banner", "label": "Site header", "bounds": { "x": 0, "y": 0, "w": 1280, "h": 64 } },
      { "id": "rgn-d4e5f6", "role": "main", "label": "Content", "bounds": { "x": 240, "y": 64, "w": 1040, "h": 656 } }
    ],
    "headings": [{ "level": 1, "text": "Dashboard", "id": "hdg-1a2b3c" }],
    "content_summary": "main: 2 headings, 5 links, 1 form"
  },
  "interactive": [
    {
      "id": "btn-a3f1c2",
      "type": "button",
      "label": "Create Project",
      "bounds": { "x": 960, "y": 80, "w": 160, "h": 40 },
      "state": {}
    }
  ],
  "forms": []
}

完整

摘要中的所有内容,加上页面上的所有可见文本内容。

详细级别

级别

令牌

使用场景

minimal

~50-200

导航后的定位。存在哪些区域?有多少交互元素?

summary

~500-5000

处理页面。完整的元素列表、表单结构、内容摘要。

full

variable

阅读页面内容。包含所有可见文本。

导航工具默认为 minimalobserve 工具默认为 summary。两者都接受可选的 detail 参数来覆盖。

元素 ID

元素 ID 在轻微的 DOM 变更中保持稳定。它们通过对元素类型、ARIA 角色、可访问名称和 DOM 路径签名的复合键进行哈希生成:

btn-a3f1c2  (button)    inp-c7e29b  (text input)
lnk-d4b910  (link)      sel-e8a3f5  (select)
chk-f1a204  (checkbox)  frm-b1d4e7  (form)
rgn-e0d2a8  (landmark)  hdg-0f4063  (heading)
dom-b2c3d9  (DOM element, from CSS selector queries)

v0.7.0 ID 格式变更: 元素 ID 哈希现在为 6 个十六进制字符(例如 btn-a3f1c2),比早期版本的 4 个字符更长。这大大减少了大型页面上跨元素的哈希冲突。硬编码或模式匹配 4 字符 ID 的代理应重新 find 元素,而不是在升级后重用缓存的 ID。

ID 在无关的 DOM 更改和同一容器内的元素重新排序中保持不变。当代理以最小详细级别导航(没有单个元素 ID)时,它使用 find 通过文本、类型或空间邻近度来定位元素——返回的元素包含可用于交互的 ID。

开发

# Run in watch mode
npm run dev

# Run all tests
npm test

# Run only unit tests
npm run test:unit

# Run only integration tests
npm run test:integration

# Type check
npx tsc --noEmit

项目结构

src/
  browser/          # Puppeteer lifecycle, tab management, CDP sessions
  renderer/         # Accessibility tree extraction, layout, content, element IDs
  state/            # Snapshot store, structural differ
  tools/            # MCP tool definitions (navigation, observation, interaction, session, dev-mode)
  dev/              # Static server, file watcher, auditor
  types/            # TypeScript interfaces
  utils/            # Logger, hash, wait utilities
tests/
  unit/             # Fast tests with mocks
  integration/      # Full Puppeteer tests against fixture HTML
  fixtures/pages/   # Test HTML files

架构

渲染器管道 是核心——它按顺序调用提取器并组装 PageRepresentation

  1. 可访问性树提取(CDP Accessibility.getFullAXTree

  2. 布局提取(CDP DOM.getBoxModel

  3. 地标、标题、交互元素和内容提取

  4. 元素 ID 生成(基于哈希,跨重新渲染稳定)

所有工具都通过 renderActivePage() 处理快照、重新加载事件、对话框检测和响应格式化。

沙盒

Charlotte 在 tests/sandbox/ 中包含一个测试网站,用于练习所有工具,而无需访问公共互联网。使用以下命令在本地提供服务:

dev_serve({ path: "tests/sandbox" })

五个页面涵盖导航、表单、交互元素、弹出窗口、延迟内容、滚动容器等。有关完整页面参考和逐工具练习清单,请参阅 docs-internal/sandbox.md

已知问题

Shadow DOM — 开放的 Shadow DOM 可以透明工作。Chromium 的可访问性树会穿透开放的 Shadow 边界,因此 Web 组件(例如 GitHub 的 <relative-time><tool-tip>)无需特殊处理即可将其内容渲染到 Charlotte 的表示中。封闭的 Shadow 根对可访问性树是不透明的,不会被捕获。

路线图

会话与配置

功能路线图

视频录制 — 将交互录制为视频,捕获代理驱动的导航和操作的完整序列,用于调试、文档和审查。

有关与 Playwright MCP 的完整差距分析,包括较低优先级的项目(视觉工具、测试/验证、跟踪、传输、安全)以及 Charlotte 具有优势的领域,请参阅 docs-internal/playwright-mcp-gap-analysis.md

完整规范

有关完整规范,包括所有工具参数、页面表示格式、元素身份策略和架构细节,请参阅 docs-internal/CHARLOTTE_SPEC.md

许可证

MIT

社区

  • 打开 bug 报告 以报告可重现的缺陷、回归或 MCP 客户端特定问题。

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有关指南,请参阅 CONTRIBUTING.md


是不断增长的文学命名 MCP 服务器套件的一部分。在 github.com/TickTockBent 查看更多。

Available Tools

23 tools
charlotte_backA

Navigate back in browser history. Returns page representation after navigation.

ParametersJSON Schema
NameRequiredDescriptionDefault
detailNo"minimal" (default), "summary" (includes content context), "full" (includes all text content)

TDQS

A3.8/5.0
Behavior3/5

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

With no annotations, the description carries the full burden. It discloses the main behavior (navigating back) and the return value (page representation), which provides some context. However, it omits important edge-case details such as behavior when there is no history, whether it waits for page load, and the exact nature of the 'page representation,' leaving gaps in transparency.

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 two concise sentences, front-loading the action and then adding the return type. There is no filler, redundancy, or unnecessary detail; every word earns its place.

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?

The tool is simple with one well-documented parameter and no annotations or output schema. The description covers the core purpose and return, which is largely sufficient. It could be improved by mentioning how the 'detail' parameter affects the returned representation or failure behavior with an empty history, but overall it is complete for a simple tool.

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?

The input schema provides 100% coverage for the single optional 'detail' parameter, including its enum and description. The tool description adds no additional parameter information, but the baseline of 3 applies given the high schema coverage.

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 ('Navigate back') and resource ('browser history'), clearly distinguishing this from sibling tools like charlotte_forward and charlotte_navigate. It also states the return value ('page representation after navigation'), leaving no ambiguity about its function.

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

Usage Guidelines3/5

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

The description implies usage by stating the action ('navigate back'), but it does not explicitly mention when to prefer this over alternatives (e.g., charlotte_forward, charlotte_navigate) or provide exclusions. There is no guidance on scenarios like empty history, but the action itself is a clear directive.

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

charlotte_clickA

Click an interactive element on the page. Returns full page representation after the click.

ParametersJSON Schema
NameRequiredDescriptionDefault
modifiersNoModifier keys to hold during click: ["ctrl"], ["shift"], ["alt"], ["meta"], or combinations like ["ctrl", "shift"]
click_typeNoClick type: "left" (default), "right", "double"
element_idYesTarget element ID from page representation

TDQS

A3.5/5.0
Behavior3/5

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

With no annotations, the description carries the full transparency burden. It does disclose that the tool returns a full page representation after the click, which is useful. However, it does not mention potential side effects like navigation, form submission, or waiting behavior, which are important for a click action.

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 two sentences, concise and front-loaded with the action and return value. Every word earns its place, with no fluff or repetition.

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

Completeness3/5

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

The description is adequate for a basic click tool, covering the action and return value. However, it lacks any mention of the sibling tool charlotte_click_at, does not explain what 'full page representation' entails, and omits potential side-effect warnings. More context is needed for full completeness.

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?

The input schema provides descriptions for all three parameters (element_id, click_type, modifiers) with 100% coverage. The description itself adds no extra parameter context, so it relies on the schema, matching the baseline score.

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

Purpose4/5

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

The description clearly states the tool clicks an interactive element on the page, which distinguishes it from scrolling, typing, and navigation. However, it does not explicitly differentiate from charlotte_click_at, which is a sibling tool likely for coordinate-based clicks, leaving the distinction implied through the word 'element'.

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

Usage Guidelines3/5

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

The phrase 'interactive element' implies element-based clicking, which suggests using this tool over charlotte_click_at, but it does not explicitly state when to use this tool versus alternatives or provide exclusions. The guidance is implied rather than explicit.

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

charlotte_click_atA

Click at specific page coordinates. Use when target elements are not in the accessibility tree (custom widgets, canvas, non-semantic interactive divs). Dispatches real CDP-level mouse events. Returns full page representation after the click.

ParametersJSON Schema
NameRequiredDescriptionDefault
xYesX coordinate in page pixels
yYesY coordinate in page pixels
modifiersNoModifier keys to hold during click: ["ctrl"], ["shift"], ["alt"], ["meta"], or combinations
click_typeNoClick type: "left" (default), "right", "double"

TDQS

A4.4/5.0
Behavior4/5

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

No annotations are provided, so the description carries full responsibility for behavioral disclosure. It reveals that the click dispatches 'real CDP-level mouse events' and returns a 'full page representation' after the click. While it doesn't cover every edge case (e.g., out-of-viewport coordinates, waiting for navigation), it provides the core behavioral traits relevant to a coordinate click tool.

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, each earning its place: action statement, usage context, and return behavior. No filler or redundancy. The structure is front-loaded with the core purpose.

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?

The tool is simple (4 params, no output schema), and the description covers the return value ('full page representation') and the type of events dispatched. It doesn't mention prerequisites like page load state, but such details are likely unnecessary for a click tool with clear semantics. Overall, it is sufficiently 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.

Parameters3/5

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

The input schema already documents all four parameters with clear descriptions, including enum values for modifiers and click_type (100% coverage). The description adds no additional parameter semantics beyond labeling x/y as 'page coordinates', so the baseline of 3 is appropriate.

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

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 function: 'Click at specific page coordinates' with a specific verb and resource. It also distinguishes itself from the sibling element-based click tool by noting it's for when elements are not in the accessibility tree (custom widgets, canvas, non-semantic interactive divs).

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 explicitly provides when-to-use guidance: 'Use when target elements are not in the accessibility tree...' This implies not to use it when elements are accessible, effectively differentiating it from alternatives like charlotte_click. The mention of CDP-level events preempts expectations about event orchestration.

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

charlotte_diffA

Compare current page state to a previous snapshot. Returns structural diff showing added, removed, moved, and changed elements.

ParametersJSON Schema
NameRequiredDescriptionDefault
scopeNo"all" (default), "structure" (landmarks/headings), "interactive" (elements/forms), "content" (text/url/title)
snapshot_idNoCompare against a specific snapshot ID (default: previous snapshot)

TDQS

A4/5.0
Behavior3/5

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

No annotations are provided, so the description carries the transparency burden. It discloses the output type (structural diff with added/removed/moved/changed elements) and implies a read-only comparison, but it doesn't explicitly state that it is non-destructive or mention prerequisites like the existence of a previous snapshot. Some behavioral context is added, but not comprehensive.

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 composed of two short sentences that front-load the primary action and the return value. There is no redundant phrasing or filler, making it highly concise and well-structured.

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?

For a tool with two optional, well-documented parameters and no output schema, the description provides the core purpose and a high-level summary of return categories. It does not explain snapshot prerequisites or error behavior, but the combination of description and schema is sufficient for the tool's apparent simplicity.

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?

The schema covers both parameters 100%, with scope enum descriptions and snapshot_id details. The tool description itself adds no additional parameter semantics beyond what the schema already provides, so the baseline of 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 uses the specific verb 'Compare' with a clear resource ('current page state to a previous snapshot') and states the return type ('structural diff showing added, removed, moved, and changed elements'). This distinguishes it from sibling tools that operate on the live page (e.g., click, type, observe) and makes the tool's purpose unambiguous.

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

Usage Guidelines4/5

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

The description provides a clear context: use this tool when you need to see differences between the current page state and a previous snapshot. It doesn't explicitly list exclusions or alternatives, but the diff focus is obvious among the siblings, which are mostly navigation and interaction tools.

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

charlotte_findA

Search for elements matching criteria. Filters interactive elements by text, role, type, or spatial proximity. Use the selector parameter to find DOM elements by CSS selector — this reaches elements not in the accessibility tree (custom widgets, non-semantic divs). Selector results return Charlotte element IDs usable with click, hover, drag, etc.

ParametersJSON Schema
NameRequiredDescriptionDefault
nearNoElement ID — find elements spatially near this one (within ~200px)
roleNoARIA role filter
textNoText content to search for (case-insensitive substring match)
typeNoInteractive element type filter (button, link, text_input, select, checkbox, etc.)
withinNoElement ID — find elements geometrically contained within this one's bounds
selectorNoCSS selector to query the DOM directly. Returns elements that may not be in the accessibility tree. Results include durable Charlotte element IDs (dom-…) that remain valid across subsequent renders and interactions, and work with fill_form; they are re-resolved against the live DOM by re-running the selector.
output_fileNoWrite the full match results to this file path instead of returning them inline. Relative paths resolve against output_dir (see charlotte_configure). Returns only a confirmation with the file path and size. Use for broad selectors (e.g. 'div', '*') that match many elements.

TDQS

A4.4/5.0
Behavior4/5

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

With no annotations, the description carries full burden and discloses important behaviors: selector reaches non-accessibility-tree elements, results return durable Charlotte element IDs re-resolved against the live DOM, and output_file writes to a file with a confirmation. It omits details on behavior when no filters are provided or whether hidden elements are included, leaving minor gaps.

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

Conciseness5/5

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

The description is well-structured: lead purpose statement, filter list, selector explanation, then output_file behavior. Every clause adds functional detail without redundancy or fluff.

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?

The description covers the main search use case, the unique selector capability, and output_file output, but does not specify the return format for inline results or behavior when no criteria are supplied. This is a minor gap given the tool's simplicity.

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 meaning beyond the schema for selector (durable IDs, re-resolution, works with fill_form) and output_file (confirmation with path and size, use for broad selectors), justifying a score 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?

The description clearly states 'Search for elements matching criteria' with specific filters (text, role, type, spatial proximity) and highlights the selector parameter for DOM access. This distinguishes it from sibling action tools like click, type, and navigate by focusing on search/find.

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

Usage Guidelines4/5

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

It explicitly recommends using the selector parameter to find elements not in the accessibility tree, providing clear contextual guidance. However, it does not explicitly state when not to use the tool or compare it to alternatives, so it stops short of full exclusionary usage advice.

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

charlotte_forwardA

Navigate forward in browser history. Returns page representation after navigation.

ParametersJSON Schema
NameRequiredDescriptionDefault
detailNo"minimal" (default), "summary" (includes content context), "full" (includes all text content)

TDQS

A4/5.0
Behavior3/5

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

No annotations are provided, so the description carries the full burden. It discloses the return behavior ('Returns page representation after navigation'), but does not specify edge cases like what happens when there is no forward history, or how 'page representation' is structured. This is adequate but minimal.

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 two concise sentences with no wasted words. It front-loads the primary action and then describes the return value, making it easy to scan.

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?

The tool is simple (one optional parameter, no output schema), and the description covers the essential purpose and return behavior. It could mention edge cases, but given the low complexity, it is reasonably complete.

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% for the single optional 'detail' parameter, with enum values and descriptions. The tool description does not add parameter information, but the schema fully documents it, so baseline 3 is 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?

The description clearly states 'Navigate forward in browser history', using a specific verb and resource. It distinguishes itself from sibling tools like charlotte_back (backward navigation) and charlotte_navigate (URL navigation).

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

Usage Guidelines4/5

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

The description clearly implies when to use this tool (when the user wants to go forward in browser history). It doesn't explicitly mention alternatives or exclusions, but the context is clear enough given the sibling tool names.

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

charlotte_navigateA

Load a URL in the active page. Returns page representation after navigation. Default minimal detail includes landmarks, headings, and interactive element counts — use charlotte_find to locate specific elements, or pass detail: 'summary' to get the full element list.

ParametersJSON Schema
NameRequiredDescriptionDefault
urlYesURL to navigate to
detailNo"minimal" (default), "summary" (includes content context), "full" (includes all text content)
timeoutNoMax wait in ms (default: 30000)
wait_forNoWait condition: "load" (default), "domcontentloaded", "networkidle". Note: "networkidle" is unreliable on SPAs with persistent WebSocket connections.

TDQS

A4.2/5.0
Behavior4/5

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

No annotations are present, so the description carries the full transparency burden. It discloses that the tool returns a page representation, specifies the default minimal detail contents (landmarks, headings, interactive element counts), and mentions the 'summary' option for more detail. While it doesn't cover failure modes, it provides meaningful behavioral context beyond a simple 'navigate' statement.

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 two sentences, front-loaded with the main action, and every phrase earns its place. It efficiently communicates the primary function, return type, default output detail, and an alternative tool reference without any fluff.

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?

For a navigation tool with no output schema, the description adequately explains the return representation and the effect of the 'detail' parameter. It also names an alternative for element location. Minor gaps exist around failure behavior and exact output semantics of the 'summary' vs 'full' detail levels, but the schema fills in parameter specifics.

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 the parameters are already well-documented. The description adds context about the default detail behavior and what the returned representation includes, which supplements the 'detail' parameter. However, it doesn't add new meaning for url, timeout, or wait_for beyond what the schema provides, keeping this at baseline 3.

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 opens with a specific verb+resource ('Load a URL in the active page') that clearly defines the tool's core function. It distinguishes itself from sibling navigation tools (back, forward, reload) by focusing on URL loading, and also clarifies its relationship to charlotte_find.

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

Usage Guidelines4/5

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

The description explicitly directs users to charlotte_find for locating specific elements, providing a clear alternative. It also explains when to use the 'summary' detail level, giving context on how to adjust output. It doesn't explicitly state when not to use navigate, but the alternative guidance is strong enough for a 4.

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

charlotte_observeA

Get current page state without performing any action. Use detail levels to control verbosity: "minimal" for landmarks, headings, and interactive element counts by landmark (use charlotte_find to get specific elements with actionable IDs, or observe({ detail: "summary" }) to see all elements), "summary" (default) for content summaries and full element list, "full" for all text content. Use view: "tree" for a compact structural outline (cheapest orientation tool), or view: "tree-labeled" to include labels on interactive elements (still much cheaper than minimal JSON, and shows which button/link/input is which).

ParametersJSON Schema
NameRequiredDescriptionDefault
viewNo"default" (structured JSON), "tree" (compact structural outline — element types only, cheapest), or "tree-labeled" (structural outline with interactive element labels — shows which button/link/input is which, still ~70% cheaper than minimal JSON)
detailNo"summary" (default), "full" (includes all text content), "minimal" (landmarks + interactive only)
selectorNoCSS selector to scope observation to a subtree
output_fileNoWrite observation data to this file path instead of returning inline. Relative paths resolve against output_dir (see charlotte_configure). Returns only a confirmation with the file path and size.
include_stylesNoInclude computed styles for visible elements (default: false)

TDQS

A4.5/5.0
Behavior4/5

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

With no annotations, the description carries the full burden of behavioral disclosure. It states 'without performing any action' (non-mutating), explains cost trade-offs ('cheapest', 'still much cheaper than minimal JSON'), and reveals output behavior for output_file ('Returns only a confirmation with the file path and size'). This provides meaningful context beyond the schema, though it omits potential error conditions or page-load requirements.

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 but well-structured: it leads with the main purpose, then explains optional parameters in a logical flow. Each sentence adds operational value without filler. Slightly longer than ideal, but the complexity of 5 parameters and absence of annotations justify the length.

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 tool's complexity (5 params, no output schema, no annotations), the description covers the essential aspects: purpose, parameter behaviors, alternatives, and cost considerations. It lacks explicit return format details for the default view, but for a read-only observation tool, the provided information is sufficient for an agent to select and invoke it correctly.

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 significant value by explaining detail level semantics (minimal/summary/full), view trade-offs (tree vs tree-labeled with cost estimates), and output_file resolution ('relative paths resolve against output_dir'). This goes beyond the bare enum names and provides actionable guidance for parameter selection.

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 function: 'Get current page state without performing any action.' The verb 'get' and resource 'page state' precisely convey the read-only nature, distinguishing it from action-oriented siblings like charlotte_click and charlotte_type. Mentioning charlotte_find and observe variants further differentiates it from element-finding tools.

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 directs when to use alternatives: 'use charlotte_find to get specific elements with actionable IDs' and 'or observe({ detail: "summary" }) to see all elements.' Recommends view: 'tree' as the 'cheapest orientation tool,' giving clear context on when to choose this tool over others.

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

charlotte_reloadA

Reload the current page. Returns page representation after reload.

ParametersJSON Schema
NameRequiredDescriptionDefault
hardNoBypass cache (default: false)
detailNo"minimal" (default), "summary" (includes content context), "full" (includes all text content)

TDQS

A3.8/5.0
Behavior3/5

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

With no annotations, the description carries the behavioral disclosure burden. It does state that the tool returns a page representation after reload, which is valuable. However, it does not mention potential side effects such as losing unsaved form state, and the 'hard' parameter's cache-bypass behavior is only in the schema, not the description.

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?

One concise sentence that immediately states the action and outcome. Every word earns its place with no filler or redundancy.

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?

For a simple reload action with two fully documented optional parameters and no output schema, the description provides adequate context: it says what the tool does and what it returns. Slightly more detail on how 'detail' affects the returned representation could improve it, but the schema already covers that.

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%: both 'hard' and 'detail' already have meaningful descriptions in the input schema. The tool description adds no additional parameter semantics, so the baseline score of 3 is 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?

The description uses a specific verb ('Reload') with a clear resource ('current page') and explicitly states the return value ('Returns page representation after reload'). It is distinct from sibling navigation tools like charlotte_navigate, charlotte_back, and charlotte_forward.

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

Usage Guidelines3/5

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

The usage context is implied: reload the current page when a refresh is needed. However, there are no explicit guidelines on when to choose this over alternatives like navigate or back/forward, nor any exclusionary conditions.

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

charlotte_screenshotA

Capture a visual screenshot. Fallback for when structured representation isn't sufficient (complex visualizations, canvas elements, images). Use save: true to persist as a file artifact that can be referenced later.

ParametersJSON Schema
NameRequiredDescriptionDefault
saveNoSave as a persistent file artifact (default: false). When true, the screenshot is written to disk and artifact metadata is returned alongside the image.
formatNo"png" (default), "jpeg", "webp"
qualityNo1-100 for jpeg/webp quality
selectorNoCSS selector to capture specific element (default: full page)
full_pageNoCapture the entire scrollable page (default: true). Set false to capture only the current viewport — much smaller output for long pages. Ignored when 'selector' is provided.
output_fileNoWrite screenshot to this file path instead of returning base64 inline. Relative paths resolve against output_dir (see charlotte_configure). Returns only a confirmation with the file path and size.

TDQS

A3.9/5.0
Behavior3/5

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

No annotations are provided, so the description carries the full transparency burden. It adds useful context about the persistent behavior of save:true and the tool's fallback role. However, it does not disclose the default return format (e.g., inline base64), whether the operation has side effects beyond saving, or that it is a read-only action. These are notable omissions for an unannotated tool, but the provided behavior hints (persistence, fallback) prevent a lower score.

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 two sentences long, front-loaded with the primary verb behavior ('Capture a visual screenshot'), then a use-case clause, then a targeted parameter tip. Every sentence earns its place; no filler or redundant restatement of the tool name.

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

Completeness3/5

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

Given the tool has 6 parameters, no output schema, and no annotations, the description does more than a minimal effort by establishing purpose and usage guidance. However, it leaves important contextual gaps: the default return format (base64) is not mentioned, and there is no hint about how to later retrieve saved artifacts (e.g., charlotte_screenshot_get). This is adequate but not fully complete for an agent making an uninformed 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 six parameters with meaningful descriptions. The description adds a bit of extra context for 'save' (persisting as a file artifact) but largely repeats what the schema explains. It neither contradicts nor significantly enhances the schema's parameter documentation, so the baseline of 3 is appropriate.

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

Purpose5/5

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

The description opens with a specific verb+resource phrase ('Capture a visual screenshot'), clearly stating the tool's core function. It further distinguishes the tool from siblings by framing it as a 'fallback for when structured representation isn't sufficient,' referencing complex visualizations, canvas elements, and images—which implicitly contrasts with observation-oriented siblings.

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

Usage Guidelines4/5

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

The description provides explicit when-to-use context: 'Fallback for when structured representation isn't sufficient' and gives concrete example cases (complex visualizations, canvas elements, images). It also offers conditional parameter guidance ('Use save: true to persist as a file artifact'). It stops short of naming a specific alternative sibling tool or outright saying 'do not use for simple text/structured content,' so it earns a 4 rather than 5.

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

charlotte_screenshot_deleteA

Delete a saved screenshot artifact by its ID. Removes the file from disk.

ParametersJSON Schema
NameRequiredDescriptionDefault
idYesScreenshot artifact ID to delete

TDQS

A4/5.0
Behavior4/5

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

With no annotations provided, the description carries the full burden of disclosing side effects. It explicitly states 'Removes the file from disk,' which conveys the destructive, persistent nature of the operation. It does not detail error handling or permissions, but for a simple delete operation, this is substantial disclosure.

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 two short sentences, front-loads the core action, and contains no filler or repetition. Every word contributes meaning.

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?

For a simple deletion tool with one parameter and no output schema, the description adequately covers the action and its effect. It does not mention how to obtain the ID or that the deletion is permanent, but the essentials are present, and the simplicity of the tool reduces the need for further context.

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?

The input schema already has 100% coverage, documenting the single 'id' parameter as 'Screenshot artifact ID to delete.' The description adds little beyond restating 'by its ID,' so the schema carries the semantic weight. This matches the baseline for high schema coverage.

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 ('Delete') and clearly identifies the resource ('saved screenshot artifact') and the required identifier ('by its ID'). It is unambiguous and distinguishes this tool from sibling tools like charlotte_screenshot_get, which retrieves rather than deletes.

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

Usage Guidelines3/5

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

The description implies when to use the tool—when a saved screenshot artifact needs to be deleted—but gives no explicit guidance about when not to use it or alternatives. It does not mention that this is the only tool for deletion or that retrieval tools should be used for other purposes.

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

charlotte_screenshot_getA

Retrieve a previously saved screenshot artifact by its ID. Returns the image data and metadata.

ParametersJSON Schema
NameRequiredDescriptionDefault
idYesScreenshot artifact ID (e.g. ss-20260224103000-a1b2c3)

TDQS

A4.3/5.0
Behavior4/5

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

With no annotations provided, the description carries the full burden. The verb 'Retrieve' clearly implies a non-destructive read-only operation, and 'Returns the image data and metadata' sets expectations for the output. No side effects or special requirements are mentioned, but for a simple retrieval tool this is sufficient.

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

Conciseness5/5

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

The description is a single, concise sentence that states the action, the target resource, and the return value without any redundant wording or 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 only one parameter and no output schema, so the description needs to explain the outcome, which it does ('Returns the image data and metadata'). For a simple getter, this is fully complete and requires no additional context.

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?

The input schema covers the only parameter 'id' with a clear description and format example. The tool description adds only 'by its ID', which reinforces the schema without adding new semantic meaning. Given 100% schema coverage, the baseline of 3 is 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?

The description uses a specific verb ('Retrieve') and resource ('saved screenshot artifact by its ID'), making the operation clear. It also distinguishes from sibling tools like charlotte_screenshot (which likely captures a new screenshot) and charlotte_screenshot_delete (which deletes) by focusing on retrieval.

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

Usage Guidelines4/5

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

The description provides clear context that this tool is for previously saved screenshots, implying it should be used when an artifact ID is already available. It does not explicitly name alternatives or exclusions, but the sibling tool names and the phrase 'previously saved' give practical usage context.

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

charlotte_screenshotsA

List all saved screenshot artifacts. Returns metadata for each saved screenshot including ID, filename, page URL, and timestamp.

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

TDQS

A4.2/5.0
Behavior3/5

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

No annotations are provided, so the description carries the burden. It discloses that the tool returns metadata (not image contents), which is useful. However, it doesn't mention pagination, limiting, ordering, or whether the list spans multiple sessions. The read-only nature is implied by 'List' but not explicitly stated. There is no contradiction with annotations since none exist.

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 consists of two short sentences that are direct and information-dense. Every word contributes: 'List', 'all saved screenshot artifacts', and the specific metadata fields. No fluff or redundancy.

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 tool's simplicity (no parameters, no output schema), the description is largely complete. It clearly states the tool lists all saved artifacts and specifies the metadata fields returned. It does not explain edge cases like empty lists or error scenarios, but for a list operation with no inputs, the provided information is sufficient for an agent to invoke it correctly.

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

Parameters4/5

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

The tool has zero parameters and the schema coverage is 100% (empty properties). The description adds no parameter details, but none are needed. By the rubric, zero params gives a baseline of 4, and the description does provide additional context about what the returned metadata includes (ID, filename, page URL, timestamp) which is helpful.

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 a specific action ('List all saved screenshot artifacts') and the resource (saved screenshots). It distinguishes from sibling tools like charlotte_screenshot (capture) and charlotte_screenshot_get (fetch one) by focusing on listing all saved artifacts.

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

Usage Guidelines4/5

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

The description clearly indicates when to use the tool: when you need to list all saved screenshot artifacts. It doesn't explicitly mention exclusions or alternatives, but the context is unambiguous given the sibling tool names. A minor gap is lack of guidance on when to use this vs. charlotte_screenshot_get or charlotte_screenshot_delete, but the primary use case is evident.

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

charlotte_scrollA

Scroll the page or a specific container. Returns full page representation after scrolling.

ParametersJSON Schema
NameRequiredDescriptionDefault
amountNoScroll amount: "page" (default), "half", or pixel value (e.g. "200")
directionYesScroll direction
element_idNoScroll within a specific container element

TDQS

A3.8/5.0
Behavior3/5

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

With no annotations provided, the description carries the full burden. It does disclose that the tool returns a full page representation after scrolling, which is useful behavioral context. However, it does not mention any potential side effects, prerequisites, or the nature of the scroll (e.g., instant, smooth). The safety/read-only nature is inferred but not stated.

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 two concise sentences: one for the action and one for the return value. There is no redundant or filler content, and the key information is front-loaded.

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

Completeness4/5

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

The tool is relatively simple with 3 parameters, all well-documented in the schema. The description covers the action and explicitly mentions the return value, which is important since there is no output schema. However, 'full page representation' is a bit vague, and the lack of annotations leaves safety assumptions implicit. Overall, it is reasonably complete for a scroll action.

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%, with each parameter (amount, direction, element_id) already described. The description adds little beyond the schema, only hinting at element_id via 'specific container'. Since the schema does the heavy lifting, a baseline score of 3 is 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?

The description uses a specific verb ('Scroll') and a resource ('page or a specific container'), which clearly differentiates it from sibling tools like charlotte_navigate or charlotte_observe. It also states the outcome ('Returns full page representation after scrolling'), making the purpose unambiguous.

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

Usage Guidelines3/5

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

No explicit guidance is given about when to use this tool versus alternatives. The usage is implied by the action itself (scrolling), but there is no mention of exclusions or alternative tools, such as using navigation for moving between pages. This is a minimum viable level of guidance.

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

charlotte_selectA

Select an option in a select/dropdown element. Returns full page representation after selection.

ParametersJSON Schema
NameRequiredDescriptionDefault
valueYesValue or text of the option to select
element_idYesTarget select element ID

TDQS

A3.8/5.0
Behavior3/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals that the tool returns a full page representation after selection, which is useful, but it does not mention side effects, prerequisites (e.g., element visibility), or event triggering. This is a basic but not comprehensive behavioral description.

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 two short sentences that immediately state the core function and the return behavior. It is front-loaded with the action, contains no fluff, and is appropriately sized for the tool's simplicity.

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?

For a simple two-parameter tool with no output schema, the description covers the essential points: what it does and what it returns. It could be marginally improved by noting that it is specifically for dropdowns, but the description and schema together provide sufficient context for an agent to use it correctly.

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?

The input schema already covers 100% of parameters with clear descriptions ('Value or text of the option to select' and 'Target select element ID'). The tool description adds no additional semantics beyond restating the purpose, so the schema is the primary source of parameter meaning.

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 action ('Select an option') and the target resource ('select/dropdown element'), making it distinct from sibling tools like charlotte_click or charlotte_type. It also notes the return behavior, further clarifying its function.

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

Usage Guidelines3/5

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

The description implies the tool is for interacting with select/dropdown elements, which provides context on when to use it. However, it does not explicitly contrast it with alternatives like charlotte_click or charlotte_toggle, nor does it mention scenarios where it should not be used.

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

charlotte_submitB

Submit a form. Can submit by form ID or by clicking its submit button. Returns full page representation after submission.

ParametersJSON Schema
NameRequiredDescriptionDefault
form_idYesForm ID from page representation

TDQS

B3/5.0
Behavior3/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does state the return value ('Returns full page representation after submission'), which is useful. However, it does not disclose that submitting a form is a mutating action with potential side effects (e.g., data changes, navigation, or irreversible submissions). The description mentions a 'clicking' method without clarifying whether it simulates a user click or requires the button to be visible, which is a behavioral gap.

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 concise at two sentences, with the primary action front-loaded. The second sentence adds return information without excessive detail. The 'Can submit by form ID or by clicking its submit button' clause is somewhat ambiguous but does not significantly bloat the description. Overall, it is appropriately sized for a simple tool.

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

Completeness3/5

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

For a tool with one parameter and no output schema, the description covers the core action and return value, which is fairly complete. However, it omits prerequisites (e.g., needing to be on a page with a form, ensuring the form_id is valid) and does not clarify the 'clicking' method. The mention of an alternative submission method without explaining how to invoke it via the schema reduces completeness. Given the tool's simplicity, a score of 3 is appropriate.

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

Parameters2/5

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

The schema covers the single parameter 'form_id' with a description ('Form ID from page representation'), giving a baseline of 3. However, the description introduces an alternative submission method ('or by clicking its submit button') that is not represented in the schema, making the parameter semantics confusing. It doesn't add meaningful detail about how form_id is used or obtained, and the alternative method could mislead the agent into expecting an additional parameter.

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

Purpose4/5

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

The description clearly states the tool's purpose: 'Submit a form.' This specifies the action (submit) and the resource (form), distinguishing it from sibling tools like charlotte_click or charlotte_type. However, the added 'Can submit by form ID or by clicking its submit button' introduces ambiguity about how submission is performed, detracting from full clarity.

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

Usage Guidelines2/5

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

The description provides no explicit guidance on when to use this tool versus alternatives like charlotte_click. It mentions two submission methods (by form ID or clicking the submit button) but does not explain when one should be preferred, nor does it contrast with sibling tools that could also perform similar actions. This leaves the agent without clear selection criteria.

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

charlotte_tab_closeA

Close a browser tab by its ID. If the closed tab was active, switches to the first remaining tab.

ParametersJSON Schema
NameRequiredDescriptionDefault
tab_idYesID of the tab to close

TDQS

A4.2/5.0
Behavior4/5

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

No annotations are provided, so the description carries the behavioral disclosure burden. It adds useful context beyond the action itself: if the closed tab was active, it switches to the first remaining tab. This discloses a side effect that an agent would not otherwise know.

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 two sentences with no redundant words. It front-loads the core action and then adds one key behavioral detail, making it easy to parse quickly.

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?

For a single-parameter tool with no output schema, the description is largely complete. It could benefit from mentioning where the tab_id comes from (e.g., from charlotte_tabs), but the sibling context and clear action make this a minor gap.

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% because the only parameter is tab_id with a clear description. The description's 'by its ID' merely restates the schema, adding no additional semantic detail about the parameter's format or source.

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 states the specific verb 'Close' and resource 'browser tab', clearly distinguishing this tool from siblings like charlotte_tab_open and charlotte_tab_switch. The addition 'by its ID' specifies the exact input needed.

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

Usage Guidelines4/5

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

The description makes the usage context obvious: use this when you want to close a browser tab. It doesn't explicitly mention alternatives, but sibling tool names (tab_open, tab_switch) provide enough differentiation to infer when this tool is appropriate.

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

charlotte_tab_openA

Open a new browser tab. Optionally navigate to a URL. The new tab becomes the active tab.

ParametersJSON Schema
NameRequiredDescriptionDefault
urlNoURL to navigate to (default: blank page)

TDQS

A4.3/5.0
Behavior4/5

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

With no annotations, the description carries the full burden. It effectively discloses the key behavioral traits: a new tab is created, optional navigation occurs, and the new tab becomes active. For a simple tool, this is sufficient, though it could mention that the previous tab remains open.

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 two concise sentences, with key information front-loaded. Every word earns its place, avoiding unnecessary detail.

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?

For a single-parameter tool with no output schema, the description fully covers the purpose and behavior. It is complete enough for an agent to select and invoke the tool correctly.

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 the url parameter already described as 'URL to navigate to (default: blank page)'. The description does not add significant new semantics beyond repeating the optionality, so baseline 3 is 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?

The description uses a specific verb ('Open') and resource ('browser tab'), clearly stating the action. It also distinguishes itself from sibling tools like charlotte_tab_switch and charlotte_tab_close by focusing on opening a new tab.

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

Usage Guidelines4/5

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

The description provides clear context: opens a new tab and optionally navigates to a URL, with the new tab becoming active. However, it does not explicitly mention when to use this tool instead of charlotte_navigate (which likely navigates the current tab), leaving a slight gap in alternative guidance.

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

charlotte_tabsA

List all open browser tabs with their URLs, titles, and active status.

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

TDQS

A4.3/5.0
Behavior4/5

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

With no annotations, the description carries the burden of behavioral disclosure. It clearly indicates a read-only listing operation and the content of the results. It does not mention pagination or ordering, but for a zero-parameter tool with straightforward behavior, this is adequately transparent.

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 a single concise sentence that front-loads the action and resource. Every word adds value, with no redundancy or 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?

For a zero-parameter, no-output-schema tool, the description fully specifies what the tool does and what information is returned. There are no missing details that would prevent an agent from using it correctly.

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?

The tool has zero parameters, and the schema coverage is 100% (vacuously). Baseline for zero parameters is 4. The description adds no parameter-specific detail because none exists, which is 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?

Description uses the specific verb 'List' and clearly identifies the resource as 'all open browser tabs', while also specifying the fields returned (URLs, titles, active status). This distinguishes it from sibling tools such as charlotte_tab_open, charlotte_tab_switch, and charlotte_tab_close.

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

Usage Guidelines3/5

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

The description implies the tool is for obtaining an overview of tabs, but it does not explicitly contrast with alternatives or state when to use this tool versus opening, switching, or closing tabs. Usage context is present but not explicit.

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

charlotte_tab_switchA

Switch to a different browser tab by its tab ID. Returns the page representation of the activated tab.

ParametersJSON Schema
NameRequiredDescriptionDefault
tab_idYesID of the tab to switch to

TDQS

A3.8/5.0
Behavior3/5

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

With no annotations provided, the description carries the burden of disclosure. It does reveal an important behavioral aspect: the tool returns the page representation of the activated tab. However, it does not mention what happens if the tab ID is invalid, whether focus changes, or any side effects beyond the switch. This is adequate but not rich.

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 two short sentences, no filler, and front-loads the action. Every word contributes to understanding the tool's purpose and return value.

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?

For a simple tool with one parameter and no output schema, the description provides the essential information: what it does and what it returns. Some details like error cases are not covered, but the tool's simplicity makes the description sufficiently complete for an agent to invoke it correctly.

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

Parameters3/5

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

The schema provides 100% coverage for the single parameter tab_id with the description 'ID of the tab to switch to'. The tool description adds minimal extra meaning beyond restating 'by its tab ID', so it does not improve on the schema. Baseline 3 is appropriate given high schema coverage.

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 ('Switch') and resource ('different browser tab') with the input identifier ('by its tab ID'). It clearly distinguishes itself from sibling tools like charlotte_tab_open and charlotte_tab_close by focusing on switching to an existing tab, and it also specifies the return value.

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

Usage Guidelines3/5

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

The description makes the basic usage clear (switch to a tab by ID) but does not explicitly state when to prefer this over alternatives like charlotte_tabs or charlotte_tab_open. There are no exclusions or prerequisites mentioned, so guidance is implied rather than explicit.

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

charlotte_toggleA

Toggle a checkbox or switch element. Returns full page representation after toggle.

ParametersJSON Schema
NameRequiredDescriptionDefault
element_idYesTarget checkbox or switch element ID

TDQS

A4/5.0
Behavior3/5

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

No annotations are provided, so the description carries the burden. It discloses the return format ('full page representation') and implies a state change by using 'toggle', but it does not detail behavior in edge cases (e.g., if already checked), potential side effects, or whether it waits for changes.

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 a single sentence that states the action, the target element type, and the return behavior. It is concise with no redundant information.

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?

For a one-parameter browser automation tool, the description adequately covers its purpose and return value. It lacks explicit prerequisites like visibility or interactability, but those are likely implied by the platform context and the simple nature of the action.

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%, and the only parameter 'element_id' is described in the schema. The tool description adds no semantic detail beyond that, so the baseline of 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 identifies the tool's action as toggling a checkbox or switch element and specifies the return value (full page representation). This distinguishes it from siblings like click, select, and submit by focusing on checkbox/switch toggle behavior.

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

Usage Guidelines4/5

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

The description implies when to use the tool: when the target element is a checkbox or switch. However, it does not explicitly contrast it with the click tool or state exclusions, so it stops short of full guidance.

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

charlotte_toolsA

Manage Charlotte tool visibility. Lists available tool groups and their status. Use 'enable' or 'disable' to control which tools are loaded. Disabled tools don't appear in the tool list — enable a group to access its tools. Groups: 'interaction' for form filling, clicking, and drag-and-drop. 'session' for cookie/auth management, tab switching, viewport, and network. 'dev_mode' for local development serving and audits. 'evaluate' for JavaScript execution. 'monitoring' for console and network request logs. 'dialog' for JavaScript dialog handling.

ParametersJSON Schema
NameRequiredDescriptionDefault
groupNoTool group to enable or disable
actionNo"list" (default) — show all groups and status. "enable"/"disable" — toggle a group.

TDQS

A4.5/5.0
Behavior4/5

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

With no annotations, the description carries the burden of disclosing behavior. It explains that disabled tools don't appear and that enabling groups is needed to use their tools. It also defines the scope of each group. It could mention persistence or side effects, but for a visibility toggle this is sufficient.

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

Conciseness5/5

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

The description is well-structured and appropriately sized. The first sentence states the purpose, the second explains behavior, and the rest enumerates groups efficiently. Every sentence provides useful information 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?

For a simple tool with two parameters, no output schema, and no annotations, the description thoroughly covers purpose, behavior, and parameter semantics. It gives enough context for an agent to select the right group and action.

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 enums, so the baseline is 3. The description adds significant value by describing what each group contains (e.g., 'interaction' for form filling/clicking) and clarifying the default 'list' action, which goes beyond the generic 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 verb+resource: 'Manage Charlotte tool visibility' and immediately explains the list/enable/disable actions. It is easy to distinguish from sibling tools, which perform specific browser actions like clicking or navigating.

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

Usage Guidelines4/5

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

The description explains when to use the tool: to list groups/status and to enable or disable groups. It also clarifies the consequence (disabled tools don't appear) and that enabling is required to access tools. It does not explicitly mention alternatives or exclusions, but the context is clear.

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

charlotte_typeA

Type text into an input element. Returns full page representation after typing.

ParametersJSON Schema
NameRequiredDescriptionDefault
textYesText to enter
slowlyNoType one character at a time with a delay between keystrokes. Use for sites with autocomplete, search-as-you-type, or per-key validation (default: false)
element_idYesTarget input element ID
clear_firstNoClear existing value before typing (default: true)
press_enterNoPress Enter after typing (default: false)
character_delayNoMilliseconds between keystrokes (implies slowly: true). Default when slowly is true: 50ms. Total typing time is capped at approximately 30s (including per-keystroke overhead); requests whose estimated duration exceeds that are rejected.

TDQS

A3.5/5.0
Behavior2/5

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

With no annotations provided, the description carries the full burden of disclosing behavioral traits. It states the return type (full page representation) but does not disclose that typing may clear existing content by default, can trigger events, or requires the element to be visible/interactable. The default clearing behavior (clear_first: true) is only discoverable through the schema, not the description.

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 two concise sentences with no wasted words. It front-loads the primary purpose and adds a useful behavioral note about the return representation, fitting the appropriate structure for a simple tool.

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

Completeness3/5

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

Despite having 6 parameters and no output schema or annotations, the description is minimal but sufficient to understand the core action. The schema covers parameter semantics, and the description states the return type. However, it lacks context about default behaviors (e.g., clearing the field, pressing Enter) that would help an agent anticipate side effects, making it adequate but not comprehensive.

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 baseline is 3. The description itself does not add meaning beyond the schema, but the schema parameters are well-documented with descriptions for each field. Since the description does not need to repeat schema details, a score of 3 is 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?

The description clearly states a specific verb ('Type') and resource ('input element'), and explicitly notes it returns the full page representation after typing. This distinguishes it from sibling tools like charlotte_click, charlotte_select, and charlotte_submit, which perform different actions.

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

Usage Guidelines3/5

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

The description implies the tool should be used when text needs to be entered into an input element, but it does not explicitly discuss when to use this tool versus alternatives, nor does it mention exclusions or prerequisites. No guidance is given for distinguishing between typing and using charlotte_submit or charlotte_click for form interactions.

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. Dates show when Glama detected each change.

  1. 23 tool updatesv0.8.0
    • Changedcharlotte_back2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_click2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_click_at2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_diff2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_find4 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
      • addedInput schema / properties / output_file
        Added value: +{
        +  "description": "Write the full match results to this file path instead of returning them inline. Relative paths resolve against output_dir (see charlotte_configure). Returns only a confirmation with the file path and size. Use for broad selectors (e.g. 'div', '*') that match many elements.",
        +  "type": "string"
        +}
      • changedInput schema / properties / selector / description
        Previous value: -"CSS selector to query the DOM directly. Returns elements that may not be in the accessibility tree. Results include Charlotte element IDs for use with interaction tools."New value: +"CSS selector to query the DOM directly. Returns elements that may not be in the accessibility tree. Results include durable Charlotte element IDs (dom-…) that remain valid across subsequent renders and interactions, and work with fill_form; they are re-resolved against the live DOM by re-running the selector."
    • Changedcharlotte_forward2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_navigate2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_observe2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_reload2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_screenshot3 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
      • addedInput schema / properties / full_page
        Added value: +{
        +  "description": "Capture the entire scrollable page (default: true). Set false to capture only the current viewport — much smaller output for long pages. Ignored when 'selector' is provided.",
        +  "type": "boolean"
        +}
    • Changedcharlotte_screenshot_delete2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_screenshot_get2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_screenshots1 field changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
    • Changedcharlotte_scroll2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_select2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_submit2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_tab_close2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_tab_open2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_tab_switch2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_tabs1 field changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
    • Changedcharlotte_toggle2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_tools2 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
    • Changedcharlotte_type7 fields changed
      • changedInput schema / $schema
        Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
      • removedInput schema / additionalProperties
        Removed value: -false
      • changedInput schema / properties / character_delay / description
        Previous value: -"Milliseconds between keystrokes (implies slowly: true). Default when slowly is true: 50ms"New value: +"Milliseconds between keystrokes (implies slowly: true). Default when slowly is true: 50ms. Total typing time is capped at approximately 30s (including per-keystroke overhead); requests whose estimated duration exceeds that are rejected."
      • removedInput schema / properties / press_enter / $ref
        Removed value: -"#/properties/clear_first"
      • addedInput schema / properties / press_enter / type
        Added value: +"boolean"
      • removedInput schema / properties / slowly / $ref
        Removed value: -"#/properties/clear_first"
      • addedInput schema / properties / slowly / type
        Added value: +"boolean"
  2. 23 tool updatesv0.6.3
    • First observedcharlotte_back
    • First observedcharlotte_click
    • First observedcharlotte_click_at
    • First observedcharlotte_diff
    • First observedcharlotte_find
    • First observedcharlotte_forward
    • First observedcharlotte_navigate
    • First observedcharlotte_observe
    • First observedcharlotte_reload
    • First observedcharlotte_screenshot
    • First observedcharlotte_screenshot_delete
    • First observedcharlotte_screenshot_get
    • First observedcharlotte_screenshots
    • First observedcharlotte_scroll
    • First observedcharlotte_select
    • First observedcharlotte_submit
    • First observedcharlotte_tab_close
    • First observedcharlotte_tab_open
    • First observedcharlotte_tab_switch
    • First observedcharlotte_tabs
    • First observedcharlotte_toggle
    • First observedcharlotte_tools
    • First observedcharlotte_type

TDQS

A3.7/5.0

Scored across 23 tools

Disambiguation5/5

Each tool has a clearly distinct purpose: navigation, tab management, interaction, observation, and screenshot management are all separated. Even similar tools like charlotte_click and charlotte_click_at are explicitly differentiated by target type (element vs coordinates).

Naming Consistency4/5

All tools share the 'charlotte_' prefix and use snake_case, but there is a mix of simple verbs (navigate, click, type) and compound verb_noun forms (tab_open, screenshot_get). This is mostly consistent but not perfectly uniform.

Tool Count3/5

With 23 tools, the server is on the heavier side but still within a manageable range for a comprehensive browser automation tool. The count is justified by the breadth of features, though it approaches the threshold where it might feel overwhelming.

Completeness4/5

Core browser automation workflows are well covered: navigation, tab management, element interaction, observation, and screenshot handling. However, the description of charlotte_tools mentions groups for dialogs, drag-and-drop, and session management, but these tools are not present in the exposed set, leaving minor gaps.

Maintenance

ActivityActive
ResponsivenessSlow

Resources

Unclaimed servers have limited discoverability.

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