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cloakbrowser-mcp

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cloakbrowser-mcp is a drop-in Playwright MCP-compatible browser automation server with unchanged upstream tools, CloakBrowser Chromium, and production-ready npm, Docker, and Streamable HTTP packaging. It runs upstream @playwright/mcp as the canonical tool surface and points that runtime at CloakBrowser.

30-second demo

30-second demo showing CloakBrowser MCP startup, humanized research prompt typing, web automation, and testing workflows

Run npx -y cloakbrowser-mcp@latest, connect Claude Desktop or Codex CLI, ask for web research, daily automation, or testing in plain English, and inspect the real browser result.

Documentation: swimmwatch.github.io/cloakbrowser-mcp · Comparison · Recipes

Use it when you need:

  • Playwright MCP browser automation backed by CloakBrowser;

  • unchanged upstream browser tools plus two local introspection tools;

  • npm or Docker installation over stdio or Streamable HTTP;

  • persistent browser profiles, validated context options, and Chrome extension loading;

  • GeoIP-aware proxy matching for regional QA;

  • humanized mouse, keyboard, and scroll behavior for interaction-sensitive flows.

Cross-platform checks cover npm on Linux x64/arm64, macOS arm64/x64, and Windows x64 across Node.js 22 and 24-26. Docker images are built and smoke-tested for linux/amd64 and linux/arm64.

See @playwright/mcp vs cloakbrowser-mcp when deciding whether plain upstream Playwright MCP or CloakBrowser MCP fits a deployment better. The Recipes pages show task-focused setup paths for persistent login profiles, Chrome extensions, reverse proxies, regional QA, client connections, and CI smoke tests.

Related MCP server: browser-devtools-mcp

Install With npm

npx -y cloakbrowser-mcp@latest

Requires Node.js 22.13+ in the 22.x line, or Node.js 24+. Run diagnostics before wiring a client:

npx -y cloakbrowser-mcp@latest doctor

For Streamable HTTP instead of stdio:

npx -y cloakbrowser-mcp@latest --transport streamable-http --http-port 3000

See the generated CLI Reference for all flags.

Install With Docker

docker run --rm --init -i \
  -v "$PWD/artifacts:/data" \
  swimmwatch/cloakbrowser-mcp:latest

For Streamable HTTP:

docker run --rm --init -p 127.0.0.1:3000:3000 \
  -v "$PWD/artifacts:/data" \
  swimmwatch/cloakbrowser-mcp:latest \
  --transport streamable-http --http-host 0.0.0.0 --http-port 3000

The Docker image writes artifacts to /data and is published for linux/amd64 and linux/arm64. It defaults to CLOAK_PLAYWRIGHT_MCP_NO_SANDBOX=true for compatibility with containerized runtimes where Chromium sandboxing is often unavailable. If your host and container runtime support Chromium sandboxing, set CLOAK_PLAYWRIGHT_MCP_NO_SANDBOX=false; for untrusted pages, keep container network access and mounted host directories tightly scoped. The same tags are also available from ghcr.io/swimmwatch/cloakbrowser-mcp. See Docker for persistent profiles, extension mounts, HTTPS, and smoke-test examples, or use the reverse proxy recipe for a focused Streamable HTTP deployment.

Add To MCP Clients

Codex CLI

codex mcp add cloakbrowser -- npx -y cloakbrowser-mcp@latest

Claude Code

claude mcp add --transport stdio cloakbrowser -- npx -y cloakbrowser-mcp@latest

GitHub Copilot In VS Code

{
  "servers": {
    "cloakbrowser": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "cloakbrowser-mcp@latest"]
    }
  }
}

Claude Desktop, Cursor, Cline, Windsurf, Warp, And Other mcpServers Clients

Add this server entry to the client's MCP JSON config:

{
  "mcpServers": {
    "cloakbrowser": {
      "command": "npx",
      "args": ["-y", "cloakbrowser-mcp@latest"]
    }
  }
}

Docker-backed stdio

{
  "mcpServers": {
    "cloakbrowser": {
      "command": "docker",
      "args": [
        "run",
        "--rm",
        "--init",
        "-i",
        "-v",
        "/tmp/cloakbrowser-artifacts:/data",
        "swimmwatch/cloakbrowser-mcp:latest"
      ]
    }
  }
}

Already-running Streamable HTTP server

npx -y cloakbrowser-mcp@latest --transport streamable-http --http-port 3000
codex mcp add cloakbrowser --url http://127.0.0.1:3000/mcp
claude mcp add --transport http cloakbrowser http://127.0.0.1:3000/mcp

Prompt For A Code Assistant

Paste this into Codex, Claude Code, Copilot, Cursor, Cline, Windsurf, or a similar coding assistant that can edit MCP config:

Install the CloakBrowser MCP server for this workspace. Name it "cloakbrowser".
Prefer stdio with command "npx" and args ["-y", "cloakbrowser-mcp@latest"].
If this client uses VS Code mcp.json, add it under "servers" with type "stdio".
If this client uses Claude/Cursor/Cline/Windsurf/Warp-style config, add it under
"mcpServers" with the same command and args. Do not add secrets.

More examples are in Getting Started, with dedicated recipes for Claude Desktop and Codex CLI.

Configuration

Use upstream PLAYWRIGHT_MCP_* variables for browser, artifacts, timeouts, network, and tool capability settings. Cloak-specific bridge toggles use CLOAK_PLAYWRIGHT_MCP_*. Select a Pro Preview browser build before startup with --release-channel preview or CLOAK_PLAYWRIGHT_MCP_RELEASE_CHANNEL=preview; the default is stable.

The common variable table now lives in Configuration. That page also covers persistent profiles, validated context options, Chrome extensions, Streamable HTTP metadata, and HTTPS/auth options. See GeoIP Proxy Matching for regional proxy behavior, Humanized Input Behavior for interaction realism, and Recipes for task-focused configurations.

Version Compatibility

cloakbrowser-mcp

@playwright/mcp

CloakBrowser

Node.js

Platform

1.13.0

^0.0.80

^0.5.10

`^22.13.0

1.12.0

^0.0.79

^0.5.7

`^22.13.0

1.11.0

^0.0.79

^0.5.6

`^22.13.0

1.10.0

^0.0.78

^0.5.3

`^22.13.0

1.9.0

^0.0.78

^0.5.1

`^22.13.0

1.8.0

^0.0.78

^0.4.10

`^22.13.0

1.7.0

^0.0.77

^0.4.8

>=22.12

npm on Linux x64/arm64, macOS arm64/x64, Windows x64; Docker linux/amd64, linux/arm64

1.6.1

^0.0.77

^0.4.7

>=22.12

npm on Linux x64/arm64, macOS arm64/x64, Windows x64; Docker linux/amd64, linux/arm64

1.6.0

^0.0.77

^0.4.7

>=22.12

npm on Linux x64/arm64, macOS arm64/x64, Windows x64; Docker linux/amd64, linux/arm64

1.5.0

^0.0.76

^0.4.3

>=22.12

npm on Linux x64/arm64, macOS arm64/x64, Windows x64; Docker linux/amd64, linux/arm64

1.4.0

^0.0.76

^0.3.32

>=22.12

npm on Linux x64/arm64, macOS arm64/x64, Windows x64; Docker linux/amd64, linux/arm64

1.3.0

^0.0.75

^0.3.31

>=20

Docker linux/amd64, Node.js local

1.2.7

^0.0.75

^0.3.30

>=20

Docker linux/amd64, Node.js local

1.2.6

^0.0.75

^0.3.30

>=20

Docker linux/amd64, Node.js local

1.2.5

^0.0.75

^0.3.30

>=20

Docker linux/amd64, Node.js local

1.2.3

^0.0.75

^0.3.30

>=20

Docker linux/amd64, Node.js local

1.2.2

^0.0.75

^0.3.30

>=20

Docker linux/amd64, Node.js local

1.2.1

^0.0.75

^0.3.30

>=20

Docker linux/amd64, Node.js local

1.2.0

^0.0.75

^0.3.30

>=20

Docker linux/amd64, Node.js local

1.1.0

^0.0.75

^0.3.30

>=20

Docker linux/amd64, Node.js local

1.0.2

^0.0.75

^0.3.30

>=20

Docker linux/amd64, Node.js local

1.0.1

^0.0.75

^0.3.30

>=20

Docker linux/amd64, Node.js local

1.0.0

^0.0.75

^0.3.30

>=20

Docker linux/amd64, Node.js local

See Version Compatibility for the maintained compatibility table.

Tools

The upstream Playwright MCP tool list is authoritative. This project does not reimplement or re-document upstream browser schemas in source code.

Local tools:

  • cloakbrowser_binary_info returns CloakBrowser package, platform, cache, and resolved binary data.

  • cloakbrowser_bridge_info returns bridge metadata, upstream package/version, and local tool names.

Development

npm install
npm run build
npm test
npm run docker:build
npm run docker:smoke
npm run server:validate
npm run bridge:compare -- cloakbrowser-mcp:dev --report bridge-parity-report.json

Documentation starts at docs/getting-started.md. Contributor material is grouped under docs/contributor-guide.md.

Available Tools

25 tools
browser_clickB
Destructive

Perform click on a web page

ParametersJSON Schema
NameRequiredDescriptionDefault
buttonNoButton to click, defaults to left
targetYesExact target element reference from the page snapshot, or a unique element selector
elementNoHuman-readable element description used to obtain permission to interact with the element
modifiersNoModifier keys to press
doubleClickNoWhether to perform a double click instead of a single click

TDQS

B3.2/5.0
Behavior3/5

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

Annotations already provide destructiveHint=true and readOnlyHint=false, indicating a modifying operation. The description adds no extra behavioral context beyond that.

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 very short and to the point. While it could be expanded slightly, it is not overly verbose.

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 simple click action with no output schema, the description is adequate but does not mention potential side effects like navigation or page changes, which are important given the openWorldHint.

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 description adds no additional meaning to the parameters beyond what's already in the schema.

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 'Perform click on a web page' clearly states the verb and resource. However, it does not differentiate from sibling tools like browser_hover or browser_press_key, which could cause confusion.

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?

No guidance on when to use this tool versus alternatives. With many sibling tools for different interactions (hover, drag, etc.), the description should specify when a click is appropriate.

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

browser_closeA
Destructive

Close the page

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

TDQS

A3.7/5.0
Behavior3/5

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

Annotations already indicate destructiveHint=true and readOnlyHint=false, so the destructive nature is clear. The description 'Close the page' adds no further behavioral context beyond what annotations provide, such as whether the entire browser session ends or just the current tab.

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 extremely concise at three words, front-loading the key information without any unnecessary text. Every word earns its place.

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 simplicity of the tool (no parameters, no output schema) and annotations that signal destructive behavior, the description is minimally adequate. However, it lacks details on scope (e.g., does it close the current page or all pages?) and side effects.

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 input schema has zero parameters with 100% description coverage. The description adds no parameter-specific meaning, but none is needed. A baseline of 4 is appropriate given the lack of parameters.

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

Purpose5/5

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

The description 'Close the page' uses a specific verb and resource, clearly distinguishing this tool from sibling tools like browser_navigate or browser_snapshot. It directly states the action and target.

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?

No guidance is provided on when to use this tool versus alternatives such as browser_navigate_back or browser_handle_dialog. The agent receives no context about prerequisites or timing.

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

browser_console_messagesB
Read-only

Returns all console messages

ParametersJSON Schema
NameRequiredDescriptionDefault
allNoReturn all console messages since the beginning of the session, not just since the last navigation. Defaults to false.
levelYesLevel of the console messages to return. Each level includes the messages of more severe levels. Defaults to "info".info
filenameNoFilename to save the console messages to. If not provided, messages are returned as text.

TDQS

B3.1/5.0
Behavior3/5

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

Annotations already indicate readOnlyHint=true and destructiveHint=false, so the safety profile is clear. The description adds no behavioral details beyond the schema, such as the default scope (since last navigation) or the effect of the 'all' parameter. With annotations present, a score of 3 is appropriate, as the description provides minimal added value.

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

Conciseness4/5

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

The description is a single concise sentence that is front-loaded. It could be slightly expanded to include more context without becoming verbose, but it is efficient.

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

Completeness2/5

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

With 3 parameters and no output schema, the description is too minimal. It does not explain the return format (text or file) or the hierarchical nature of the 'level' parameter (though schema covers it). The description is incomplete for effective tool usage.

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 each parameter already has a clear description. The tool description adds no additional meaning beyond what the schema provides. Baseline score of 3 is correct.

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 'Returns all console messages' clearly states the verb (returns) and resource (console messages). It is specific enough to distinguish from sibling tools like browser_snapshot or browser_network_requests, though it could explicitly mention the browser context.

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?

No guidance on when to use this tool versus alternatives such as browser_run_code_unsafe for executing code and checking console, or browser_evaluate for expression results. The description lacks any when-to-use or when-not-to-use information.

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

browser_dragC
Destructive

Perform drag and drop between two elements

ParametersJSON Schema
NameRequiredDescriptionDefault
endTargetYesExact target element reference from the page snapshot, or a unique element selector
endElementNoHuman-readable target element description used to obtain the permission to interact with the element
startTargetYesExact target element reference from the page snapshot, or a unique element selector
startElementNoHuman-readable source element description used to obtain the permission to interact with the element

TDQS

C2.9/5.0
Behavior2/5

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

Annotations indicate destructive and open world, but description adds no behavioral context (e.g., possible side effects, event triggers).

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

Conciseness4/5

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

Single sentence is concise and front-loaded. Could benefit from structured details but no waste.

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

Completeness2/5

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

Lacks context about page state, element requirements, or interaction flow. No output schema, so return behavior is undocumented.

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?

Schema descriptions are vague ('human-readable...'), and tool description adds no clarification. Baseline 3 lowered due to weak 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 action ('drag and drop') and the resource ('elements'), distinguishing it from siblings like browser_click and browser_drop.

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?

No guidance on when to use this tool vs alternatives (e.g., browser_drop, browser_click). Missing context on prerequisites or conditions.

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

browser_dropA
Destructive

Drop files or MIME-typed data onto an element, as if dragged from outside the page. At least one of "paths" or "data" must be provided.

ParametersJSON Schema
NameRequiredDescriptionDefault
dataNoData to drop, as a map of MIME type to string value (e.g. {"text/plain": "hello", "text/uri-list": "https://example.com"}).
pathsNoAbsolute paths to files to drop onto the element.
targetYesExact target element reference from the page snapshot, or a unique element selector
elementNoHuman-readable element description used to obtain permission to interact with the element

TDQS

A4.2/5.0
Behavior4/5

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

Annotations already mark destructiveHint as true, and the description aligns by stating 'Drop...' implying mutation. The description adds valuable context by specifying it simulates an external drag-and-drop, which goes beyond what annotations provide. No contradictions.

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

Conciseness5/5

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

Two sentences, no extraneous information. Every part contributes: the action, the simulation aspect, and the parameter constraint. Highly efficient.

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 moderate complexity (4 parameters, nested data object, no output schema), the description covers the core functionality and a key constraint. It could further elaborate on typical use cases or interactions with other browser tools, but is largely sufficient.

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

Parameters4/5

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

Schema coverage is 100%, but the description adds a critical usage condition ('At least one of paths or data must be provided') not enforced by the schema. It also implicitly clarifies the purpose of each parameter. While not exhaustive, it adds meaningful semantic value.

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 clearly states the action ('Drop files or MIME-typed data') and target ('onto an element'), with a specific simulation context ('as if dragged from outside the page'). It effectively distinguishes from sibling tools like browser_drag, which likely handles internal drag-and-drop.

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 provides a necessary constraint ('At least one of paths or data must be provided') but lacks explicit guidance on when to use this tool over alternatives such as browser_file_upload for standard file inputs. No comparison with siblings is given.

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

browser_evaluateC
Destructive

Evaluate JavaScript expression on page or element

ParametersJSON Schema
NameRequiredDescriptionDefault
targetNoExact target element reference from the page snapshot, or a unique element selector
elementNoHuman-readable element description used to obtain permission to interact with the element
filenameNoFilename to save the result to. If not provided, result is returned as text.
functionYes() => { /* code */ } or (element) => { /* code */ } when element is provided

TDQS

C2.8/5.0
Behavior2/5

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

The description adds no behavioral information beyond what the annotations already provide (readOnlyHint=false, destructiveHint=true). It doesn't mention potential side effects, security implications, or the fact that it can be destructive.

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

Conciseness3/5

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

The description is very concise (one sentence), but it is under-specified. It lacks important details and could benefit from elaboration without harming conciseness.

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

Completeness2/5

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

Given the tool's ability to execute arbitrary JavaScript, which can be destructive (as indicated by annotations), the description is incomplete. It doesn't cover return values, error handling, or behavioral nuances, and there is no output schema.

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 has 100% description coverage for parameters. The tool description does not add any additional meaning beyond the schema, so a baseline of 3 is appropriate.

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

Purpose4/5

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

The description clearly states it evaluates JavaScript expressions on a page or element, which is the core purpose. However, it doesn't differentiate from the sibling tool browser_run_code_unsafe, which likely has a similar purpose.

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?

No guidance is provided on when to use this tool versus alternatives like browser_run_code_unsafe or other browser interaction tools. The description lacks any context for appropriate usage.

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

browser_file_uploadA
Destructive

Upload one or multiple files

ParametersJSON Schema
NameRequiredDescriptionDefault
pathsNoThe absolute paths to the files to upload. Can be single file or multiple files. If omitted, file chooser is cancelled.

TDQS

A3.5/5.0
Behavior3/5

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

The description adds minimal behavioral context beyond the annotations. Annotations indicate destructiveHint=true (potential side effects) and openWorldHint=true, which the description does not elaborate on. It does not mention that the upload may open a file dialog, require an active file input, or that omitting paths cancels the operation (though this is covered in the schema).

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 extremely concise at just four words, with no wasted text. However, it could be slightly more structured (e.g., including a note about the file chooser or multiple file support) without losing conciseness.

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

Completeness2/5

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

Given that there is no output schema and the tool interacts with the browser environment, the description lacks contextual completeness. It does not explain what happens after upload (e.g., whether the tool waits for completion, if the page refreshes, or how to verify success). The schema covers cancellation, but the overall usage context is insufficiently described for an agent to understand the full behavior.

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 provides full coverage (100%) of the 'paths' parameter, including a description that explains its meaning and the cancellation behavior. The description adds no additional semantic value beyond what is in the schema.

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

Purpose5/5

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

The description clearly states the verb 'Upload' and the resource 'one or multiple files', which is specific and distinct from all sibling browser tools that focus on clicks, navigation, form filling, etc. It leaves no ambiguity about what the tool does.

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

Usage Guidelines3/5

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

The description implies that this tool is used for uploading files via the browser, but it does not provide explicit guidance on when to use it (e.g., after navigating to a page with a file input) or when not to (e.g., if the goal is to download files). No alternative tools are mentioned.

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

browser_fill_formC
Destructive

Fill multiple form fields

ParametersJSON Schema
NameRequiredDescriptionDefault
fieldsYesFields to fill in

TDQS

C2.8/5.0
Behavior2/5

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

Annotations indicate destructiveHint=true and readOnlyHint=false, so the description's 'fill' aligns, but it offers no additional behavioral context (e.g., whether form submission occurs, fields are cleared first, or error handling). The description adds no value beyond the structured annotations.

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

Conciseness3/5

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

The description is extremely short (4 words), which is concise but at the cost of informativeness. It does not front-load critical details like input format or behavior, making it less actionable.

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

Completeness2/5

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

Given the tool has no output schema, a single required parameter with nested structure, and destructiveHint=true, the description should explain return values (e.g., success confirmation) and side effects. It provides neither, leaving significant gaps.

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 field property well-documented in the schema itself. The tool description adds no extra meaning or usage examples, 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.

Purpose4/5

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

The description 'Fill multiple form fields' clearly states the action (fill) and resource (multiple form fields). However, it does not distinguish this tool from siblings like browser_type (single field) or browser_select_option, which reduces 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 guidance on when to use this tool versus alternatives such as browser_type or browser_select_option, or what prerequisites exist (e.g., form must be present). Agents are left guessing about appropriate contexts.

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

browser_handle_dialogC
Destructive

Handle a dialog

ParametersJSON Schema
NameRequiredDescriptionDefault
acceptYesWhether to accept the dialog.
promptTextNoThe text of the prompt in case of a prompt dialog.

TDQS

C2.1/5.0
Behavior2/5

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

Annotations indicate destructiveHint=true and readOnlyHint=false, but the description adds no behavioral context. It does not explain that handling a dialog accepts or dismisses it, nor does it describe any side effects. The description adds no value beyond the annotations.

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

Conciseness2/5

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

Extremely short at 4 words, but under-specification harms clarity. It is not appropriately sized; lacks essential detail for an agent to use correctly.

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

Completeness1/5

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

With 2 parameters and no output schema, the description is critically incomplete. It fails to explain the dialog lifecycle, when to use this tool, or the behavior of accept/promptText. The agent cannot adequately understand the tool's purpose and constraints.

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 parameters accept (required boolean) and promptText (optional string) are well-documented in schema. Description adds no extra meaning; baseline 3 is appropriate.

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

Purpose2/5

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

Description is 'Handle a dialog', which is a verb+resource but vague. It does not specify what 'handle' means (e.g., accept/reject) or differentiate from sibling tools. It essentially restates the title, making it borderline tautological.

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?

No guidance on when to use this tool vs alternatives. It does not mention that dialogs appear from browser prompts (alert, confirm, prompt) or that this tool should be used after a dialog is triggered. Missing context for appropriate use.

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

browser_hoverC
Destructive

Hover over element on page

ParametersJSON Schema
NameRequiredDescriptionDefault
targetYesExact target element reference from the page snapshot, or a unique element selector
elementNoHuman-readable element description used to obtain permission to interact with the element

TDQS

C2.9/5.0
Behavior2/5

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

Annotations indicate destructiveHint=true and readOnlyHint=false, suggesting side effects, but the description adds no behavioral context beyond 'hover over element'. Does not disclose potential UI changes or state modifications.

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

Conciseness4/5

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

Single sentence, front-loaded, no redundant information. Could be slightly more informative without harming conciseness, but current form is efficient.

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 simple operation and rich schema, description is adequate but incomplete. Missing context about requiring a snapshot, event triggering, or return value expectations. No output schema, but description does not compensate.

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?

Input schema covers both parameters with descriptions, achieving 100% coverage. The tool description does not add further meaning, so baseline 3 is appropriate. No additional value from description.

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?

Description states a clear action (hover) and resource (element on page), distinguishing it from sibling tools like click, drag, or type. However, it does not elaborate on what hover triggers (e.g., tooltips, popups), leaving some ambiguity about the exact purpose.

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?

No guidance on when to use hover versus alternatives like click or drag. Missing prerequisites (e.g., need a page snapshot) or exclusions. Implied use is when hovering is needed, but no context for selection.

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

browser_navigateA
Destructive

Navigate to a URL

ParametersJSON Schema
NameRequiredDescriptionDefault
urlYesThe URL to navigate to

TDQS

A3.7/5.0
Behavior3/5

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

Annotations already provide destructiveHint=true and openWorldHint=true. Description adds no further behavioral context (e.g., that it loads a new page and may lose current page state). Acceptable with annotations present.

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

Conciseness5/5

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

Single, focused sentence. No redundant information. Front-loaded and efficient.

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?

Adequate for a simple tool with 1 param and no output schema. However, lacks usage guidelines relative to siblings and does not mention validity requirements for the URL, leaving room for improvement.

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% and param description is clear. Description does not add meaning beyond the schema, so baseline 3 applies.

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

Purpose5/5

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

Clearly states action (Navigate) and resource (URL). Distinct from sibling tools like browser_click or browser_close that perform other 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?

No explicit when-to-use or when-not-to-use guidance. Implied use for loading a new page, but does not distinguish from browser_navigate_back or mention prerequisites like having a current page.

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

browser_navigate_backA
Destructive

Go back to the previous page in the history

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

TDQS

A4.1/5.0
Behavior3/5

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

Annotations already declare destructiveHint=true and readOnlyHint=false. The description adds no behavioral details beyond stating the action, such as potential side effects (e.g., form data loss) or session behavior. With annotations, the bar is lower, but the description contributes no additional 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 a single sentence with no extraneous information. It is front-loaded and efficient.

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

Completeness5/5

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

Given no parameters and no output schema, the description fully covers the tool's purpose. No additional context is needed for this simple 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?

The tool has zero parameters, so schema description coverage is 100%. The description adds no parameter information, which is acceptable. Baseline is 4.

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

Purpose5/5

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

The description 'Go back to the previous page in the history' uses a specific verb ('Go back') and resource ('previous page'), clearly distinguishing it from sibling tools like browser_navigate (goes to a specific URL) and browser_click.

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 does not provide explicit when-to-use or when-not-to-use guidance. While the action is simple, it lacks context about prerequisites (e.g., whether there is a previous page) or alternatives. Usage is implied but not clarified.

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

browser_network_requestA
Read-only

Returns full details (headers and body) of a single network request, or a single part if part is set. Use the number from browser_network_requests.

ParametersJSON Schema
NameRequiredDescriptionDefault
partNoReturn only this part of the request. Omit to return full details.
indexYes1-based index of the request, as printed by browser_network_requests.
filenameNoFilename to save the result to. If not provided, output is returned as text.

TDQS

A4.2/5.0
Behavior3/5

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

Annotations already indicate readOnly=true; description adds behavioral detail about optional part retrieval and file saving, but no further side effects are disclosed. Adequate but not exceptional.

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

Conciseness5/5

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

Two concise sentences, front-loaded with action and resource, no 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?

Covers key usage (index, part, filename) and relationship to sibling. Missing explicit return format details, but acceptable given no output schema.

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?

100% schema coverage, description adds usage context: index from sibling, part enumeration, optional filename. Adds value beyond 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?

Description clearly states 'Returns full details of a single network request' with verb and resource, and distinguishes from sibling by referencing the number from browser_network_requests.

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

Usage Guidelines4/5

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

Provides clear context that the index comes from browser_network_requests, implying sequential usage. Does not explicitly state when not to use, but alternatives are differentiated.

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

browser_network_requestsA
Read-only

Returns a numbered list of network requests since loading the page. Use browser_network_request with the number to get full details.

ParametersJSON Schema
NameRequiredDescriptionDefault
filterNoOnly return requests whose URL matches this regexp (e.g. "/api/.*user").
staticYesWhether to include successful static resources like images, fonts, scripts, etc. Defaults to false.
filenameNoFilename to save the network requests to. If not provided, requests are returned as text.

TDQS

A4.2/5.0
Behavior4/5

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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds useful behavioral context: requests are listed since page load, and it returns a numbered list. No contradictions. Could mention if the list is cleared on navigation, but not necessary.

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

Conciseness5/5

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

Two sentences, front-loaded with the primary action, immediately followed by usage guidance. Every word is functional, no 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?

The tool has no output schema, but the description indicates it returns a 'numbered list' and directs to the detail tool. This is sufficient for a simple list tool. Could be improved by hinting at the list format (e.g., URLs or titles), but not necessary.

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%; each parameter already has clear descriptions. The tool description does not add new meaning to the parameters beyond what the schema provides, so 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 clearly states 'Returns a numbered list of network requests since loading the page,' specifying the verb, resource, and scope. It distinguishes from the sibling browser_network_request by indicating that the full details are obtained via that tool with the corresponding number.

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: use this tool to get a list, then use browser_network_request for details. It mentions optional filters (static, filter, filename) but does not explicitly state when not to use this tool (e.g., if direct detail is needed).

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

browser_press_keyC
Destructive

Press a key on the keyboard

ParametersJSON Schema
NameRequiredDescriptionDefault
keyYesName of the key to press or a character to generate, such as `ArrowLeft` or `a`

TDQS

C2.9/5.0
Behavior2/5

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

Annotations indicate destructiveHint and readOnlyHint, but the description adds no further behavioral context (e.g., focus requirement, key combination handling).

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

Conciseness3/5

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

The description is very short, which aids conciseness, but it may be under-specified as it lacks important context that could fit in a few extra words.

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's simplicity and available annotations, the description is minimally adequate but omits details like usage context and potential side effects.

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% and the parameter description is clear; the tool description adds no additional meaning beyond the schema.

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 'Press a key on the keyboard' clearly states the action and resource, but does not differentiate from sibling tools like browser_type or browser_click, which could be confused.

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?

No guidance is provided on when to use this tool versus alternatives, such as when to press a single key versus typing text or clicking.

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

browser_resizeB
Destructive

Resize the browser window

ParametersJSON Schema
NameRequiredDescriptionDefault
widthYesWidth of the browser window
heightYesHeight of the browser window

TDQS

B3.1/5.0
Behavior2/5

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

The description adds no behavioral context beyond the annotations. Annotations declare destructiveHint: true, but the description does not explain what 'destructive' means (e.g., it may break existing page layout or affect viewport). The agent is left to infer behavior from the name alone.

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 with no superfluous words. It is front-loaded and efficient, which is optimal 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?

Given the tool's simplicity (no output schema, two simple numeric params), the description is minimally adequate. However, it lacks mention of return value or side effects (e.g., whether the window resizing triggers events or is synchronous). For complete guidance, more detail would be needed.

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 both parameters described as 'Width/Height of the browser window'. The description does not add extra meaning such as units (pixels?), valid ranges, or that both parameters are required. Baseline 3 is appropriate since schema already documents parameters adequately.

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 resizes the browser window, using a specific verb+resource. While it does not distinguish from sibling tools, no sibling performs resizing, so differentiation is unnecessary. However, it lacks specificity about what 'resize' means (e.g., does it set exact dimensions or relative adjustment?).

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?

No guidance is provided on when to use this tool versus alternatives. For example, it doesn't mention that resizing might be needed before screenshotting or that other tools like browser_navigate depend on window size. No exclusions or context are given.

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

browser_run_code_unsafeA
Destructive

Run a Playwright code snippet. Unsafe: executes arbitrary JavaScript in the Playwright server process and is RCE-equivalent.

ParametersJSON Schema
NameRequiredDescriptionDefault
codeNoA JavaScript function containing Playwright code to execute. It will be invoked with a single argument, page, which you can use for any page interaction. For example: `async (page) => { await page.getByRole('button', { name: 'Submit' }).click(); return await page.title(); }`
filenameNoLoad code from the specified file. If both code and filename are provided, code will be ignored.

TDQS

A3.7/5.0
Behavior4/5

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

Beyond annotations (destructiveHint true, openWorldHint true), the description adds specific risk information: 'executes arbitrary JavaScript in the Playwright server process and is RCE-equivalent.' This clarifies the nature of the destructiveness.

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-loaded with the primary action and immediately followed by the key warning. Every word is informative with no redundancy.

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?

While the schema covers parameters, the description does not mention what the tool returns (e.g., result of code execution). Given no output schema, this is a gap. However, the core purpose and risk are adequately communicated.

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 both parameters well. The tool description adds no extra information about parameters beyond what the schema provides. Baseline score 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 'Run a Playwright code snippet,' specifying the action and resource. It also distinguishes from sibling tools like browser_evaluate by noting that it executes JavaScript in the server process, not the page context.

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 warns that it is unsafe and RCE-equivalent, but does not provide explicit guidance on when to use this tool versus alternatives such as browser_evaluate. No conditions or exclusions are mentioned.

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

browser_select_optionB
Destructive

Select an option in a dropdown

ParametersJSON Schema
NameRequiredDescriptionDefault
targetYesExact target element reference from the page snapshot, or a unique element selector
valuesYesArray of values to select in the dropdown. This can be a single value or multiple values.
elementNoHuman-readable element description used to obtain permission to interact with the element

TDQS

B3.3/5.0
Behavior2/5

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

Annotations already indicate destructiveHint=true, but the description adds no further behavioral context about side effects, such as triggering change events or page modifications. It merely restates the action.

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

Conciseness4/5

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

The description is a single, precise sentence with no wasted words, though it lacks additional structure or examples.

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

Completeness2/5

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

The description is too brief given the lack of output schema; it does not explain return values, error cases, or what happens after selection, leaving significant gaps for an agent.

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

Parameters3/5

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

Schema coverage is 100%, so the description adds no extra parameter meaning beyond what the schema already provides. 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 'Select an option in a dropdown' clearly states the verb (select) and the resource (option in a dropdown), making it distinct from sibling tools like browser_click or browser_fill_form.

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 context (dropdown selection) but provides no explicit guidance on when to use versus alternatives, nor any exclusions.

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

browser_snapshotB
Read-only

Capture accessibility snapshot of the current page, this is better than screenshot

ParametersJSON Schema
NameRequiredDescriptionDefault
boxesNoInclude each element's bounding box as [box=x,y,width,height] in the snapshot. Coordinates are viewport-relative, in CSS pixels (Element.getBoundingClientRect)
depthNoLimit the depth of the snapshot tree
targetNoExact target element reference from the page snapshot, or a unique element selector
filenameNoSave snapshot to markdown file instead of returning it in the response.

TDQS

B3/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=true and destructiveHint=false, reducing the burden on description. The description adds a quality claim but does not disclose behavior like snapshot format or response structure.

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

Conciseness4/5

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

Single sentence is concise and front-loaded with purpose and comparative value. Slightly short for a tool with 4 parameters, but no extraneous content.

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

Completeness2/5

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

Tool has no output schema and 4 optional parameters; description does not explain the return format or parameter effects beyond schema. Incomplete for an AI agent to understand full 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?

Schema description coverage is 100%, so parameters are well-documented in schema. The description adds no extra semantic meaning beyond the schema.

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

Purpose3/5

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

The description states it captures an accessibility snapshot and claims it is better than screenshot, but 'accessibility snapshot' is vague without further definition. It differentiates from screenshot but lacks specificity on what the snapshot contains.

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?

Implies usage for accessibility via the comparative statement 'better than screenshot', but does not explicitly state when to use or not use this tool, nor provide alternative tool names.

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

browser_tabsB
Destructive

List, create, close, or select a browser tab.

ParametersJSON Schema
NameRequiredDescriptionDefault
urlNoURL to navigate to in the new tab, used for new.
indexNoTab index, used for close/select. If omitted for close, current tab is closed.
actionYesOperation to perform

TDQS

B3.3/5.0
Behavior3/5

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

Annotations already indicate destructiveHint=true and readOnlyHint=false, so the description adds minimal behavioral context beyond listing the operations. The agent can infer that 'new' and 'close' are destructive, while 'list' and 'select' are not, but no additional warnings or side effects are mentioned.

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 efficiently lists all possible operations. It is front-loaded with the key purpose and contains no unnecessary words.

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 covers the basic operations but lacks information about return values. For example, the 'list' action likely returns a list of tabs, but the description doesn't mention this. Given no output schema, this omission reduces 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?

Schema coverage is 100%, so parameters are well-documented. The description does not add any extra meaning beyond what the schema provides for action, index, and url. Baseline score is appropriate.

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 it can list, create, close, or select a browser tab, which matches the action enum. However, it does not distinguish itself from sibling tools like 'browser_close' or 'browser_navigate', which could lead to confusion about which tool to use for specific operations.

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 guidance on when to use this tool versus alternatives like 'browser_close' or 'browser_navigate'. For instance, it's unclear whether to use 'browser_tabs' with action 'close' or the sibling 'browser_close' tool for closing a tab.

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

browser_take_screenshotA
Read-only

Take a screenshot of the current page. You can't perform actions based on the screenshot, use browser_snapshot for actions.

ParametersJSON Schema
NameRequiredDescriptionDefault
typeYesImage format for the screenshot. Default is png.png
targetNoExact target element reference from the page snapshot, or a unique element selector
elementNoHuman-readable element description used to obtain permission to interact with the element
filenameNoFile name to save the screenshot to. Defaults to `page-{timestamp}.{png|jpeg}` if not specified. Prefer relative file names to stay within the output directory.
fullPageNoWhen true, takes a screenshot of the full scrollable page, instead of the currently visible viewport. Cannot be used with element screenshots.

TDQS

A4.6/5.0
Behavior5/5

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

The description adds behavioral context beyond annotations: it states that you cannot perform actions based on the screenshot, which is not covered by readOnlyHint or destructiveHint. This is valuable for an AI agent.

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?

Very concise: two sentences with no wasted words. The critical guidance 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?

Given the tool's simplicity and the rich schema/annotations, the description is mostly complete. However, it could mention the return format (e.g., base64 image or file) since there is no output schema.

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

Parameters3/5

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

Schema coverage is 100%, so baseline is 3. The description does not add additional meaning to the parameters beyond what the schema already provides.

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

Purpose5/5

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

The description clearly states the action (take a screenshot) and the resource (current page), and distinguishes it from the sibling tool browser_snapshot by specifying that you cannot perform actions on the screenshot.

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

Usage Guidelines5/5

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

Explicitly tells when to use the tool (taking a screenshot) and when not to (for actions), and provides an alternative (browser_snapshot). This is high-quality guidance.

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

browser_typeB
Destructive

Type text into editable element

ParametersJSON Schema
NameRequiredDescriptionDefault
textYesText to type into the element
slowlyNoWhether to type one character at a time. Useful for triggering key handlers in the page. By default entire text is filled in at once.
submitNoWhether to submit entered text (press Enter after)
targetYesExact target element reference from the page snapshot, or a unique element selector
elementNoHuman-readable element description used to obtain permission to interact with the element

TDQS

B3.4/5.0
Behavior3/5

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

Annotations already indicate destructiveHint=true and openWorldHint=true, and the description is consistent. However, it adds no extra behavioral context beyond the obvious 'typing text'—it doesn't mention triggering events, page navigation, or permission requirements.

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, efficient sentence with no wasted words. It front-loads the core action and target, making it easy to scan.

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

Completeness2/5

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

With 5 parameters (including nuanced ones like 'submit' and 'slowly') and no output schema, the description is insufficient. It does not explain return behavior, prerequisites (e.g., need for a page snapshot), or the effect of 'openWorldHint=true' on external systems.

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 each parameter's purpose is already documented. The description adds no additional insight beyond what's in the schema, earning a baseline score of 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 clearly states the action ('Type text') and the resource ('into editable element'), which is specific and distinguishes it from sibling tools like browser_click or browser_fill_form.

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 guidance on when to use this tool versus alternatives (e.g., browser_fill_form for form fields, browser_press_key for single keys). There are no exclusion criteria or usage context.

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

browser_wait_forA
Read-only

Wait for text to appear or disappear or a specified time to pass

ParametersJSON Schema
NameRequiredDescriptionDefault
textNoThe text to wait for
timeNoThe time to wait in seconds
textGoneNoThe text to wait for to disappear

TDQS

A3.8/5.0
Behavior3/5

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

The description adds context about waiting for text, which is beyond the annotations (readOnlyHint), but lacks details on polling behavior, timeout handling, or error conditions. The behavioral traits are only partially disclosed.

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, well-structured sentence that is front-loaded and contains no superfluous 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 simple tool with no output schema and three optional parameters, the description covers the core functionality. However, it omits specifics like default timeout or behavior when no parameter is provided, leaving minor gaps.

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 description adds limited extra meaning beyond restating parameter names. It does not clarify mutual exclusivity of parameters or default behavior.

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 waits for text appearance, disappearance, or a timeout. This distinguishes it from sibling tools like browser_click or browser_navigate, 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 usage for waiting on page conditions, but does not provide explicit guidance on when to use this tool versus alternatives, nor does it mention prerequisites or limitations.

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

cloakbrowser_binary_infoCloakBrowser binary infoA
Read-onlyIdempotent

Return CloakBrowser package, cache, platform, and resolved browser binary information.

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

TDQS

A4.2/5.0
Behavior4/5

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

Annotations already indicate readOnlyHint=true and idempotentHint=true. The description adds specificity about the returned data (package, cache, platform, resolved browser binary), which provides behavioral context beyond annotations. No contradictions.

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?

A single sentence that is direct and informative, with no redundant words. Every word adds 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?

Given zero parameters and no output schema, the description provides sufficient context by enumerating the types of information returned. However, it lacks details about the output structure (e.g., nested fields), which might be inferred but not explicit.

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 schema description coverage is 100% trivially. The description adds no parameter information, but none is needed. Baseline for no parameters is 4.

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

Purpose5/5

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

The description clearly states the tool's function: returning CloakBrowser package, cache, platform, and resolved browser binary information. It uses a specific verb ('Return') and resource ('binary info'), distinguishing it from sibling tools that perform browser actions or return bridge info.

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 on when to use this tool versus alternatives. While the distinction from sibling tools is implicit through the description, the description lacks any statements about context, prerequisites, or when to prefer this over others.

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

cloakbrowser_bridge_infoCloakBrowser bridge infoA
Read-onlyIdempotent

Return runtime metadata for the CloakBrowser bridge over upstream Playwright MCP.

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

TDQS

A3.5/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is clear. The description adds no additional behavioral context beyond stating it returns metadata. Acceptable but doesn't exceed annotation coverage.

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

Conciseness5/5

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

Single sentence, front-loaded with purpose, no unnecessary words. Perfectly concise and 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?

Tool has no parameters and no output schema, but annotations provide safety context. The description is sufficient for a simple info tool, though briefly hinting at return format would be helpful for completeness.

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?

No parameters, so the description does not need to add parameter info. Schema coverage is 100% (empty). Baseline 4 is appropriate for zero parameters.

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 returns runtime metadata for the CloakBrowser bridge. It specifies verb ('Return'), resource ('runtime metadata'), and context ('CloakBrowser bridge over upstream Playwright MCP'), distinguishing it from sibling browser tools. Could be more specific about what metadata includes, but effective.

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?

No guidance on when to use this tool versus alternatives like cloakbrowser_binary_info or other browser tools. No 'when-to-use', 'when-not-to-use', or special conditions provided. Implicitly it's for bridge info but lacks explicit context.

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. 1 tool updatev1.10.0
    • Addedbrowser_network_request
  2. 1 tool updatev1.9.0
    • Removedbrowser_network_request
  3. 25 tool updatesv1.0.0
    • First observedbrowser_click
    • First observedbrowser_close
    • First observedbrowser_console_messages
    • First observedbrowser_drag
    • First observedbrowser_drop
    • First observedbrowser_evaluate
    • First observedbrowser_file_upload
    • First observedbrowser_fill_form
    • First observedbrowser_handle_dialog
    • First observedbrowser_hover
    • First observedbrowser_navigate
    • First observedbrowser_navigate_back
    • First observedbrowser_network_request
    • First observedbrowser_network_requests
    • First observedbrowser_press_key
    • First observedbrowser_resize
    • First observedbrowser_run_code_unsafe
    • First observedbrowser_select_option
    • First observedbrowser_snapshot
    • First observedbrowser_tabs
    • First observedbrowser_take_screenshot
    • First observedbrowser_type
    • First observedbrowser_wait_for
    • First observedcloakbrowser_binary_info
    • First observedcloakbrowser_bridge_info

TDQS

B3.4/5.0
Disambiguation5/5

Each tool has a distinct purpose (e.g., click vs hover, snapshot vs screenshot). The two network-related tools are clearly differentiated, and all browser actions are well-separated. No overlaps that would cause confusion.

Naming Consistency5/5

All tools follow a consistent snake_case pattern with the 'browser_' prefix, except two 'cloakbrowser_' tools which still follow the same style. Verbs are clear and uniform.

Tool Count4/5

With 25 tools, the set is slightly large but still well-scoped for comprehensive browser automation. Each tool covers a needed action, and the count is reasonable for the domain.

Completeness4/5

The tool set covers all major browser interactions: navigation, clicking, typing, form filling, file upload, drag-and-drop, screenshots, snapshots, console/network monitoring, dialogs, tabs, and even unsafe execution. Minor gaps like cookie management exist, but overall it is very thorough.

Maintenance

ActivityActive
ResponsivenessResponsive

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