CloakBrowser MCP
The CloakBrowser MCP server is a browser automation tool that runs Playwright with a CloakBrowser (stealth Chromium) backend, enabling AI agents to control a browser for web interactions.
Navigate & Control the Browser
Navigate to URLs, go back, close the browser, resize the window, and manage tabs (list, create, close, select)
Interact with Web Elements
Click (left/right/middle, double-click), type text, fill forms, press keyboard keys, hover, drag-and-drop, select dropdown options, upload files, and drop files/data onto elements
Inspect & Capture Page State
Take screenshots (
browser_take_screenshot), capture accessibility snapshots (browser_snapshot), retrieve console messages (browser_console_messages), and list/inspect network requests (browser_network_requests,browser_network_request)
Scripting & Automation
Execute JavaScript on the page (
browser_evaluate), run arbitrary Playwright code (browser_run_code_unsafe— use with caution), and wait for text to appear/disappear or a timeout (browser_wait_for)
Handle Browser Events
Accept or dismiss dialogs (alerts, confirms, prompts) via
browser_handle_dialog
Diagnostics & Metadata
Retrieve CloakBrowser binary details (
cloakbrowser_binary_info) and bridge runtime metadata including upstream Playwright MCP version and available tools (cloakbrowser_bridge_info)
Allows GitHub Copilot in VS Code to control a CloakBrowser browser for web automation, including form filling, network request inspection, and JavaScript evaluation.
Integrates Warp terminal with browser automation capabilities via MCP, enabling AI-powered web interaction within the terminal environment.
cloakbrowser-mcp
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

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@latestRequires Node.js 22.13+ in the 22.x line, or Node.js 24+. Run diagnostics before wiring a client:
npx -y cloakbrowser-mcp@latest doctorFor Streamable HTTP instead of stdio:
npx -y cloakbrowser-mcp@latest --transport streamable-http --http-port 3000See the generated CLI Reference for all flags.
Install With Docker
docker run --rm --init -i \
-v "$PWD/artifacts:/data" \
swimmwatch/cloakbrowser-mcp:latestFor Streamable HTTP:
docker run --rm --init -p 127.0.0.1:3000:3000 \
-v "$PWD/artifacts:/data" \
swimmwatch/cloakbrowser-mcp:latest \
--transport streamable-http --http-host 0.0.0.0 --http-port 3000The 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@latestClaude Code
claude mcp add --transport stdio cloakbrowser -- npx -y cloakbrowser-mcp@latestGitHub 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/mcpPrompt 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 |
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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_inforeturns CloakBrowser package, platform, cache, and resolved binary data.cloakbrowser_bridge_inforeturns 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.jsonDocumentation starts at docs/getting-started.md. Contributor material is grouped under docs/contributor-guide.md.
Available Tools
25 toolsbrowser_clickBDestructive
Perform click on a web page
| Name | Required | Description | Default |
|---|---|---|---|
| button | No | Button to click, defaults to left | |
| target | Yes | Exact target element reference from the page snapshot, or a unique element selector | |
| element | No | Human-readable element description used to obtain permission to interact with the element | |
| modifiers | No | Modifier keys to press | |
| doubleClick | No | Whether to perform a double click instead of a single click |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=false and destructiveHint=true, indicating the tool mutates state and can be destructive. The description adds no further behavioral disclosure, such as possible navigation or permission requirements. It does not contradict annotations, but provides no value beyond them.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single concise sentence with no filler. However, it is terse and omits useful context that could be added without bloat, such as the requirement for a snapshot target. It is appropriately sized but not front-loaded with any distinguishing information.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's moderate complexity (5 parameters, no output schema), the description alone is minimally sufficient because the schema fully describes parameters. However, it lacks context about return values, when to use click vs other actions, and potential side effects. The schema covers parameter semantics, so 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.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, with every parameter documented (e.g., target is 'Exact target element reference from the page snapshot, or a unique element selector'). The description itself adds no additional parameter meaning, so the baseline of 3 applies.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action ('Perform click') and the resource ('web page'), which is specific enough. However, it does not differentiate from sibling interaction tools like browser_hover or browser_drag; the agent must infer that 'click' is a distinct action without additional context. It is unambiguous about the core operation but lacks detail on the target element requirement.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides no guidance on when to use this tool versus alternatives. It does not mention prerequisites such as needing a page snapshot to obtain a valid target, nor does it contrast with browser_hover or browser_drag. An agent receives no context for tool selection.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_closeBDestructive
Close the page
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotation already indicates destructiveHint=true, so the agent knows the action is destructive. The description simply repeats that by saying 'close' without adding any extra context about side effects (e.g., whether it closes just the current tab, loses unsaved state, or affects other tabs). It does not contradict the annotation, but it adds no new behavioral information.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is extremely concise, using only three words. It communicates the essential action and target without any fluff, making it easy to parse and understand quickly.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the simplicity of the tool (no parameters, no output schema), the description is functional but lacks completeness. It leaves open the scope of 'close'—does it close the current page/tab, or the entire browser? In a context with sibling tools like browser_tabs, this ambiguity could be problematic. More detail would improve it.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
There are no parameters, so the schema coverage is trivially complete at 100%. The description does not need to explain any parameter semantics, and the baseline score of 3 applies.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description 'Close the page' clearly states the action (close) and the resource (page), making it unambiguous. It is distinct from sibling tools like browser_navigate or browser_snapshot, so an agent can easily identify it.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides no guidance on when to use this tool versus alternatives. It does not mention potential alternatives (e.g., using browser_tabs to manage multiple pages) or any conditions that would make closing appropriate. The context is minimal and leaves the decision entirely to the agent.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_console_messagesBRead-only
Returns all console messages
| Name | Required | Description | Default |
|---|---|---|---|
| all | No | Return all console messages since the beginning of the session, not just since the last navigation. Defaults to false. | |
| level | Yes | Level of the console messages to return. Each level includes the messages of more severe levels. Defaults to "info". | info |
| filename | No | Filename to save the console messages to. If not provided, messages are returned as text. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate readOnlyHint true and destructiveHint false, so the description adds no conflicting side-effect information. It does not elaborate on behavior such as saving to a file, but that is covered by parameter descriptions.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single clear sentence with no redundancy, front-loading the verb and object.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple read-only tool with full schema coverage, the description is adequate, though it omits explicit use-case guidance and output format details beyond what the schema provides.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% with detailed parameter descriptions, so the tool description itself does not add meaning beyond the schema, but no parameter meaning is missing.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
Description uses a specific verb 'Returns' and identifies the resource 'console messages' with scope 'all', making the tool's purpose clear and distinct from sibling tools such as network request retrieval.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No guidance is provided on when to use this tool versus alternatives like browser_network_requests or browser_snapshot, nor does it mention filtering or filename-saving scenarios.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_dragADestructive
Perform drag and drop between two elements
| Name | Required | Description | Default |
|---|---|---|---|
| endTarget | Yes | Exact target element reference from the page snapshot, or a unique element selector | |
| endElement | No | Human-readable target element description used to obtain the permission to interact with the element | |
| startTarget | Yes | Exact target element reference from the page snapshot, or a unique element selector | |
| startElement | No | Human-readable source element description used to obtain the permission to interact with the element |
TDQS
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 covered. The description adds no extra behavioral context such as side effects on the DOM or event firing, but it does not contradict 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.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single concise sentence that front-loads the action and provides the core information without any irrelevant detail.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple action with well-described parameters and no output schema, the description is mostly complete. It does not mention any return values or wait behavior, but the lack of output schema makes this acceptable. It could have added a note about the order of start and end parameters, but the parameter names and descriptions handle that.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100% with all four parameters described. The tool description adds no additional parameter semantics beyond what the schema already provides, so the baseline of 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action (perform drag and drop) and the resource (between two elements), distinguishing it from sibling tools like browser_click, browser_hover, and browser_drop. It is specific and unambiguous.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description does not provide any guidance on when to use this tool versus alternatives. It does not mention conditions such as needing to move an element or triggering drag-and-drop events, nor does it reference sibling tools like browser_drop or browser_click.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_dropADestructive
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.
| Name | Required | Description | Default |
|---|---|---|---|
| data | No | Data to drop, as a map of MIME type to string value (e.g. {"text/plain": "hello", "text/uri-list": "https://example.com"}). | |
| paths | No | Absolute paths to files to drop onto the element. | |
| target | Yes | Exact target element reference from the page snapshot, or a unique element selector | |
| element | No | Human-readable element description used to obtain permission to interact with the element |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already convey destructive and non-read-only behavior, so the description does not need to repeat that. The description adds useful semantic context about simulating an external drag, but does not disclose any side effects beyond the basic drop action.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, focused sentence that concisely explains both the action and the key parameter requirement. No filler or redundancy.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description, combined with the detailed schema and annotations, provides enough information to invoke the tool correctly. There is no output schema, so return-value details are not required, and the parameter permission explanation is handled by the 'element' field description.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
All parameters have clear schema descriptions. The tool description adds an important cross-parameter constraint that at least one of 'paths' or 'data' must be provided, which is not otherwise expressed in the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action: dropping files or MIME-typed data onto an element. It uses a specific verb and resource, and distinguishes itself from in-page drag operations by specifying 'as if dragged from outside the page'.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives a useful usage constraint ('At least one of paths or data must be provided') and hints at external drag context, but it does not explicitly name sibling tools or state when to prefer this over browser_file_upload or browser_drag.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_evaluateBDestructive
Evaluate JavaScript expression on page or element
| Name | Required | Description | Default |
|---|---|---|---|
| target | No | Exact target element reference from the page snapshot, or a unique element selector | |
| element | No | Human-readable element description used to obtain permission to interact with the element | |
| filename | No | Filename to save the result to. If not provided, result is returned as text. | |
| function | Yes | () => { /* code */ } or (element) => { /* code */ } when element is provided |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already flag destructiveHint=true and readOnlyHint=false, so the agent knows this can modify state. The description adds minimal context beyond that—it mentions 'on page or element' but doesn't warn about the power of arbitrary JS execution or potential side effects. Since the annotation covers the destructive nature, the description's lack of extra detail keeps it at a baseline 3.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single, clear sentence with no redundant words. The action is front-loaded and easy to parse. This is appropriately concise for a tool whose parameter details are already in the schema.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given that this tool executes arbitrary JavaScript with destructive potential, the description is too sparse. It doesn't mention that the function can modify the page, that results can be saved to a file (though schema covers it), or that there is a separate unsafe variant (browser_run_code_unsafe) that might be more appropriate for certain tasks. The description lacks the context an agent needs to safely and correctly use this tool, especially when annotations already warn about destructiveness but the description provides no additional guidance.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so all four parameters are documented in the schema itself. The description does not add any meaning beyond what the schema provides—it doesn't elaborate on the function syntax, target usage, or filename behavior. With high schema coverage, the baseline is 3, and the description contributes nothing extra.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the verb 'Evaluate' and the resource 'JavaScript expression on page or element', making the core purpose obvious. However, it doesn't distinguish from the sibling browser_run_code_unsafe, which might also execute code, so it loses a point for not differentiating between similar tools.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
There is no guidance on when to use this tool versus alternatives like browser_run_code_unsafe or when to avoid it. No context about prerequisites (e.g., page must be loaded) or scenarios that favor this tool over others. The description simply states the action without any usage direction.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_file_uploadBDestructive
Upload one or multiple files
| Name | Required | Description | Default |
|---|---|---|---|
| paths | No | The absolute paths to the files to upload. Can be single file or multiple files. If omitted, file chooser is cancelled. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotations already indicate destructive behavior and non-read-only semantics, so the description does not need to restate those. However, the description does not mention side effects beyond uploading, such as navigating away, opening or cancelling a file chooser, or potential overwrite behavior, though the parameter description partially covers the cancellation case.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is extremely concise and free of filler. Every word contributes meaning, and the parameter description adds necessary details without redundancy.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple one-parameter tool with no output schema, the description and parameter comment cover the essential input and basic behavior. However, it does not describe what happens after the upload, what success or failure looks like, or how this fits into the broader browser automation workflow, leaving some practical context missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema only defines an array of strings, but the parameter description adds important meaning: paths must be absolute, multiple files are allowed, and omitting the parameter cancels the file chooser. This goes beyond the raw schema and helps an agent use the parameter correctly.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action ('Upload') and the resource ('files'), and specifies 'one or multiple'. It does not explicitly state the destination or context, but the tool name and sibling set make the browser file-upload intent sufficiently clear.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives no guidance on when to use this tool versus alternatives such as browser_drop or other browser interaction tools. It also does not mention prerequisites like whether the file chooser must already be open or how paths should be formatted beyond 'absolute'.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_fill_formBDestructive
Fill multiple form fields
| Name | Required | Description | Default |
|---|---|---|---|
| fields | Yes | Fields to fill in |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotations already declare readOnlyHint=false and destructiveHint=true, so the write and potentially destructive nature is covered. The description adds the 'multiple form fields' detail but does not disclose additional behavior such as overwriting values or submitting the form.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single clear sentence with no redundant words or boilerplate. It is appropriately short and easy to parse, though it sacrifices deeper context for brevity.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The rich schema fully documents the nested field objects, including target references, type-specific value behavior, and permission-related element descriptions. Combined with the read-only and destructive annotations, the description is sufficient for correct invocation; only alternative-selection guidance is missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%: the fields array and its nested target, name, type, value, and element properties all have descriptive text. The description itself does not add parameter-level meaning beyond what the schema already provides.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description 'Fill multiple form fields' clearly identifies the action and resource, and the word 'multiple' helps distinguish it from single-field tools like browser_type. It does not explicitly contrast with sibling tools, but the core purpose is unambiguous.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No guidance is provided for when to use this tool instead of alternatives such as browser_type, browser_select_option, or browser_click. The term 'multiple' implies batch usage, but there is no explicit when-to-use or exclusion context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_handle_dialogCDestructive
Handle a dialog
| Name | Required | Description | Default |
|---|---|---|---|
| accept | Yes | Whether to accept the dialog. | |
| promptText | No | The text of the prompt in case of a prompt dialog. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotations indicate readOnlyHint=false and destructiveHint=true, covering the main safety aspect. However, the description adds no detail about side effects, such as submitting a form or canceling a prompt, beyond what the parameter names imply. It does not clearly disclose the consequences of accepting or rejecting.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is extremely short and lacks necessary detail, making it under-specified. It is terse but not informative enough to guide an agent effectively, similar to a placeholder like 'Process'.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
No output schema or additional context is provided. The description does not explain what happens after handling the dialog, how the parameters interact, or any post-conditions. This is insufficient for an agent to fully understand the tool's behavior.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% with clear descriptions for both 'accept' (boolean) and 'promptText' (string for prompt dialogs). The description does not add extra meaning, but the schema already provides adequate parameter semantics, so the baseline of 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description 'Handle a dialog' identifies the action and resource but is vague. It does not specify the type of dialog (alert, confirm, prompt) or the precise effect, though the 'accept' parameter implies accept/dismiss. It is distinct from sibling tools, but the purpose is under-specified.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No guidance is provided about when to use this tool, such as after a dialog appears or in contrast to other browser actions. The description gives no context for the appropriate situation.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_hoverADestructive
Hover over element on page
| Name | Required | Description | Default |
|---|---|---|---|
| target | Yes | Exact target element reference from the page snapshot, or a unique element selector | |
| element | No | Human-readable element description used to obtain permission to interact with the element |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate readOnlyHint=false and destructiveHint=true, so the description doesn't need to re-state them. The description adds no extra behavioral detail about side effects (e.g., triggering JavaScript events, potential menu changes). With annotations present, the bar is lower, but there's still room for more transparency about outcomes.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is extremely concise—six words, no redundancy, and perfectly focused on the action. It follows a clear verb-object structure with no extra fluff, making it easy to parse and understand.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple interaction tool, the description, alongside the parameter schema and annotations, is adequate. It lacks details on return values (but no output schema exists) and does not mention any prerequisites or setup. Given the simplicity, it covers essential context without being overlong.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Both parameters (target and element) have descriptions in the schema, achieving 100% coverage. The tool description does not add further meaning beyond the schema; it simply restates the action. Since schema coverage is complete, 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.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action (hover) and the target (element on page). It distinguishes itself from sibling tools like click, drag, and type by specifying the hover action. However, it lacks detail about what the hover does (e.g., showing tooltips or hover menus), but the core purpose is clear.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives no explicit guidance on when to use hover versus other interactions. While it's intuitive that hover is for mouse-over actions, the description doesn't mention edge cases or alternative tools (e.g., use click for activating, hover for previews). It provides minimal implicit usage context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_network_requestARead-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.
| Name | Required | Description | Default |
|---|---|---|---|
| part | No | Return only this part of the request. Omit to return full details. | |
| index | Yes | 1-based index of the request, as printed by browser_network_requests. | |
| filename | No | Filename to save the result to. If not provided, output is returned as text. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and destructiveHint=false, covering safety. The description adds that it returns headers and body and can filter to a part, but does not elaborate on output structure or edge cases. Given annotation coverage, a 3 is appropriate.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two sentences with no redundant wording. The main purpose is front-loaded, the part option is explained, and the source of the index is given. Every sentence earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a read-only retrieval tool with full schema coverage and annotations, the description is sufficient. It explains the return type (full details or part) and the index source. It lacks explicit output format details, but the enum values for 'part' are self-explanatory.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% with descriptions for all parameters, so the schema already documents them. The description adds critical value by explaining that 'index' comes from browser_network_requests, which is not in the schema, enhancing clarity.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool returns full details of a single network request, with an optional 'part' parameter to narrow down. It distinguishes from the sibling tool browser_network_requests by referencing its index, making the purpose unambiguous.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The instruction 'Use the number from browser_network_requests' explicitly guides when to use this tool—after obtaining a listing. It does not explicitly mention alternatives or exclusions, but the context is clear enough for an agent to decide.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_network_requestsARead-only
Returns a numbered list of network requests since loading the page. Use browser_network_request with the number to get full details.
| Name | Required | Description | Default |
|---|---|---|---|
| filter | No | Only return requests whose URL matches this regexp (e.g. "/api/.*user"). | |
| static | Yes | Whether to include successful static resources like images, fonts, scripts, etc. Defaults to false. | |
| filename | No | Filename to save the network requests to. If not provided, requests are returned as text. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds valuable context about the temporal scope ('since loading the page') and the numbered list format, which goes beyond annotations without contradicting them.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two concise sentences with no redundancy. The primary action is front-loaded, and the companion tool reference is placed efficiently at the end. Every word earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description tells the agent what the tool returns (a numbered list) and how to proceed for details. Since there is no output schema, this is essential. It does not describe potential error cases or edge scenarios, but for a read-only list tool with strong schema coverage, it is sufficiently complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
All three parameters have schema descriptions covering 100% of the input schema. The tool description does not add any additional meaning to the parameters themselves, so the baseline of 3 applies; it neither enhances nor detracts from what the schema already provides.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states it returns a numbered list of network requests since page load, and explicitly differentiates from the sibling tool browser_network_request by instructing to use that tool for details. This is a specific verb+resource with a clear scope.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives an explicit usage pattern: first call this tool to get a list, then use browser_network_request with the number for full details. This is clear guidance on when to use it versus its companion, though it does not mention any other alternatives or exclusions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_press_keyBDestructive
Press a key on the keyboard
| Name | Required | Description | Default |
|---|---|---|---|
| key | Yes | Name of the key to press or a character to generate, such as `ArrowLeft` or `a` |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description does not mention any side effects, such as triggering keyboard events or potential destructive behavior. The annotations indicate destructiveHint: true, but the description adds no additional 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.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is extremely concise — a single sentence that directly conveys the action. No unnecessary information or repetition.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple action with a single well-defined parameter, the description is adequate. It lacks mention of when to use this tool (e.g., for shortcuts or navigation keys) but is otherwise complete for basic invocation.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The parameter 'key' is fully described in the schema with examples, and schema coverage is 100%. The description adds minimal extra meaning ('on the keyboard') but doesn't clarify key formats or special keys, which is already covered by the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action (press) and the resource (key on the keyboard). It is distinct from broader actions like navigate or click, though it does not explicitly differentiate from browser_type (typing) or browser_click (clicking).
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No guidance is provided on when to use this tool versus its siblings (e.g., browser_type for text entry or browser_click for mouse actions). The description lacks any contextual cues for choosing this tool.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_resizeBDestructive
Resize the browser window
| Name | Required | Description | Default |
|---|---|---|---|
| width | Yes | Width of the browser window | |
| height | Yes | Height of the browser window |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description does not disclose any behavioral traits beyond the bare action. Annotations already indicate it is not read-only and is destructive, but the description adds no extra context about side effects like layout reflows or potential viewport changes.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, short declarative sentence with no unnecessary words. It is perfectly concise and well-structured for the simple action it describes.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple tool, the description is adequate, but it lacks any extra context such as units (e.g., pixels), constraints, or when resizing might be appropriate. Given the simplicity and schema coverage, it is minimally complete but not rich.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema already provides descriptions for both parameters (width and height), achieving 100% coverage. The description adds no additional meaning about the parameters, so it stays at the baseline of 3.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action (resize) and the resource (browser window), making it distinct from sibling tools like navigate or click. However, it lacks any nuance about whether it resizes the viewport or the entire window, but the core purpose is clear.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No guidance is provided about when to use this tool versus alternatives. It does not mention scenarios like adjusting viewport for responsive testing or any conditions that would make it preferable to other navigation tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_run_code_unsafeADestructive
Run a Playwright code snippet. Unsafe: executes arbitrary JavaScript in the Playwright server process and is RCE-equivalent.
| Name | Required | Description | Default |
|---|---|---|---|
| code | No | A 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(); }` | |
| filename | No | Load code from the specified file. If both code and filename are provided, code will be ignored. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true and openWorldHint=true, so the description's 'Unsafe: executes arbitrary JavaScript in the Playwright server process and is RCE-equivalent' adds specific severity and mechanism beyond the generic flags. This enhances transparency without contradicting annotations, though it could also mention side effects or sandboxing if any.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single sentence that packs purpose and a crucial warning. It front-loads the action and immediately follows with the risk, maximizing information density with zero filler. Excellent structure.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's complexity (arbitrary code execution) and the lack of an output schema, the description does not mention the return value or error behavior. The example in the code parameter shows a return, but that's in the schema. For an advanced tool, this is a notable gap, but the core purpose and danger are clear. A 3 reflects the missing return semantics and operational details.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema covers 100% of parameters with detailed descriptions, including the precedence rule for code vs filename. The tool description adds no additional parameter meaning beyond the schema, so a baseline of 3 is appropriate. The schema does the heavy lifting.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action: 'Run a Playwright code snippet.' It specifies the resource (Playwright code) and immediately flags the critical distinction from siblings with 'Unsafe: executes arbitrary JavaScript ... RCE-equivalent.' This unambiguous verb+resource plus the danger label leaves no ambiguity about what the tool does and separates it from all other browser tools.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives a strong warning about safety ('Unsafe', 'RCE-equivalent') but does not explicitly state when to use it versus alternatives. It implies it's for advanced custom logic, but there is no direct 'use this only if...' or mention of safer alternatives. The warning serves as a caution but not a full usage guide.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_select_optionBDestructive
Select an option in a dropdown
| Name | Required | Description | Default |
|---|---|---|---|
| target | Yes | Exact target element reference from the page snapshot, or a unique element selector | |
| values | Yes | Array of values to select in the dropdown. This can be a single value or multiple values. | |
| element | No | Human-readable element description used to obtain permission to interact with the element |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate destructive=true, so the description does not contradict that. But the description adds no further behavioral detail (e.g., side effects on the page). With annotations present, the bar is lower, and the description is neutral.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single concise sentence with no redundant words. It is well-structured and to the point.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool is simple and the schema covers all parameters. The description is short but sufficient for a basic understanding. It does not specify whether values are labels or values, but that is a minor omission given the context.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% with clear parameter descriptions for target and values. The tool description itself does not explain parameters beyond what the schema already provides, so it adds no extra semantic value.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action (select) and the target (option in a dropdown), distinguishing it from more general actions like click or type. However, it does not explicitly contrast with sibling tools, so it misses a bit of distinction.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides no guidance on when to use this tool versus alternatives. It does not mention when selecting is appropriate or when other actions (e.g., click, type) might be preferred.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_snapshotBRead-only
Capture accessibility snapshot of the current page, this is better than screenshot
| Name | Required | Description | Default |
|---|---|---|---|
| boxes | No | Include each element's bounding box as [box=x,y,width,height] in the snapshot. Coordinates are viewport-relative, in CSS pixels (Element.getBoundingClientRect) | |
| depth | No | Limit the depth of the snapshot tree | |
| target | No | Exact target element reference from the page snapshot, or a unique element selector | |
| filename | No | Save snapshot to markdown file instead of returning it in the response. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is clear. The description adds 'capture' but no further behavioral detail beyond what annotations convey.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single concise sentence. The phrase 'this is better than screenshot' adds some comparative value but could be considered slightly extraneous.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
There is no output schema and the description does not explain what format the snapshot takes, how parameters like depth or target affect the result, or what kind of accessibility information is included. This leaves important context missing for an agent deciding whether and how to call the tool.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema covers all 4 parameters with descriptions, so the baseline is 3. The description does not add any additional parameter meaning or usage notes beyond the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a clear action ('capture') and object ('accessibility snapshot of the current page'), and distinguishes itself from screenshot with a comparative remark, though 'better than screenshot' is somewhat vague.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Gives minimal guidance by saying 'better than screenshot', but does not explicitly state when to use this tool over alternatives like browser_evaluate or browser_console_messages, nor when not to use it.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_tabsADestructive
List, create, close, or select a browser tab.
| Name | Required | Description | Default |
|---|---|---|---|
| url | No | URL to navigate to in the new tab, used for new. | |
| index | No | Tab index, used for close/select. If omitted for close, current tab is closed. | |
| action | Yes | Operation to perform |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true and readOnlyHint=false, so the safety profile is known. However, the description adds no behavioral context beyond what the schema provides (e.g., index omission for close closes current tab is in schema). No mention of side effects like tab switching or browser-level changes.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single sentence that efficiently lists all supported actions. It is front-loaded with verbs and avoids unnecessary words.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool has multiple actions and a required action parameter. The description lists the actions but does not explain action-specific requirements (e.g., URL required for new, index for close/select) or edge cases like closing the last tab. Given the schema covers parameter details, the description is adequate but not rich. With no output schema, the agent must infer return values from the action.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100% with each parameter having a description (url, index, action with enum). The tool description adds no parameter-level detail, so it does not go beyond schema. Baseline 3 applies.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool's purpose with specific verbs (list, create, close, select) and a specific resource (browser tab). It distinguishes from siblings like browser_close (closes the entire browser) and browser_navigate (navigates current tab) by focusing on tab operations.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description implies usage through the list of actions but provides no explicit when-to-use guidance or exclusions. Given siblings like browser_close (closes the entire browser) and browser_navigate (navigates current tab), an agent might benefit from explicit differentiation, but the actions themselves are clear enough that usage is implied.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_take_screenshotARead-only
Take a screenshot of the current page. You can't perform actions based on the screenshot, use browser_snapshot for actions.
| Name | Required | Description | Default |
|---|---|---|---|
| type | Yes | Image format for the screenshot. Default is png. | png |
| target | No | Exact target element reference from the page snapshot, or a unique element selector | |
| element | No | Human-readable element description used to obtain permission to interact with the element | |
| filename | No | File 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. | |
| fullPage | No | When true, takes a screenshot of the full scrollable page, instead of the currently visible viewport. Cannot be used with element screenshots. |
TDQS
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.
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.
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.
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.
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.
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_typeBDestructive
Type text into editable element
| Name | Required | Description | Default |
|---|---|---|---|
| text | Yes | Text to type into the element | |
| slowly | No | Whether to type one character at a time. Useful for triggering key handlers in the page. By default entire text is filled in at once. | |
| submit | No | Whether to submit entered text (press Enter after) | |
| target | Yes | Exact target element reference from the page snapshot, or a unique element selector | |
| element | No | Human-readable element description used to obtain permission to interact with the element |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotation destructiveHint=true and readOnlyHint=false already signal that this tool can modify state, so the description does not contradict that. However, the main description adds no additional behavioral context beyond the annotations, such as whether typing overwrites existing content or triggers page events. The parameter descriptions do mention key-handler triggering and Enter submission, but the main description itself stays shallow.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, focused sentence with no filler or repetition. It front-loads the verb and object, making the tool's primary purpose immediately obvious.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool with several closely related siblings (fill_form, press_key, click), the description is too thin to fully orient an agent. It lacks any mention of when typing is appropriate, how the target is resolved, or what side effects to expect, so the agent must rely on parameter descriptions and external context to make a confident choice.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the baseline is 3 because the input schema already documents all five parameters. The main description, 'Type text into editable element,' adds no meaning beyond the schema's parameter descriptions, which already define text, slowly, submit, target, and element clearly enough.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a clear action ('Type text') and a clear target ('editable element'), which distinguishes it from many sibling tools at a high level. It is slightly vague about whether 'editable element' includes textareas, contenteditable regions, or only input fields, but the core purpose is unambiguous.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives no guidance on when to prefer this tool over sibling tools such as browser_fill_form or browser_press_key. It does not mention exclusions, prerequisites, or scenarios where typing would be inappropriate, leaving the agent to infer usage from the tool name alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
browser_wait_forARead-only
Wait for text to appear or disappear or a specified time to pass
| Name | Required | Description | Default |
|---|---|---|---|
| text | No | The text to wait for | |
| time | No | The time to wait in seconds | |
| textGone | No | The text to wait for to disappear |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description adds behavioral detail beyond the readOnlyHint by explaining that it waits for text appearance/disappearance or a time delay. However, it does not specify what happens if multiple parameters are provided or if none are provided, so behavior is not fully transparent.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single concise sentence that front-loads the core action and conditions. It contains no unnecessary words and is easy to parse.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple wait tool with no output schema, the description covers the main use cases, but it omits edge cases such as default behavior when no parameters are supplied, timeout behavior, or error conditions. These gaps make it only partially complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema descriptions already cover each parameter individually, and the tool description mostly restates them. It does not clarify the relationship between text, textGone, and time (e.g., whether they are mutually exclusive or combinable), so minimal semantic value is added beyond the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool waits for a condition: text to appear, text to disappear, or a specified time to pass. This distinguishes it from sibling tools like click, navigate, or type, and its purpose is immediately understandable.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description implies when to use the tool (when waiting for page state or a delay), but it does not explicitly state when to prefer this over alternatives or how to choose among text, textGone, and time parameters. It provides functional guidance but lacks explicit usage conditions.
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 infoARead-onlyIdempotent
Return CloakBrowser package, cache, platform, and resolved browser binary information.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
TDQS
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.
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.
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.
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.
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.
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 infoARead-onlyIdempotent
Return runtime metadata for the CloakBrowser bridge over upstream Playwright MCP.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
TDQS
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.
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.
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.
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.
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.
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.
1 tool update
v1.10.0- Added
browser_network_request
1 tool update
v1.9.0- Removed
browser_network_request
25 tool updates
v1.0.0- First observed
browser_click - First observed
browser_close - First observed
browser_console_messages - First observed
browser_drag - First observed
browser_drop - First observed
browser_evaluate - First observed
browser_file_upload - First observed
browser_fill_form - First observed
browser_handle_dialog - First observed
browser_hover - First observed
browser_navigate - First observed
browser_navigate_back - First observed
browser_network_request - First observed
browser_network_requests - First observed
browser_press_key - First observed
browser_resize - First observed
browser_run_code_unsafe - First observed
browser_select_option - First observed
browser_snapshot - First observed
browser_tabs - First observed
browser_take_screenshot - First observed
browser_type - First observed
browser_wait_for - First observed
cloakbrowser_binary_info - First observed
cloakbrowser_bridge_info
TDQS
Scored across 25 tools
Several tools have closely related purposes, such as browser_drag vs browser_drop, browser_close vs browser_tabs, and browser_fill_form vs browser_type. The descriptions mostly clarify the differences, but an agent could still easily select the wrong one in edge cases.
The browser_ prefix is consistent, but the naming patterns vary between bare verbs (browser_click), verb+object (browser_select_option), and noun phrases (browser_tabs, browser_file_upload). The two cloakbrowser_* info tools also break the overall naming scheme, though they are clearly metadata-oriented.
At 25 tools, this is on the heavier end for a tool set. Most tools serve a real browser-automation purpose, but a few are arguably redundant or very niche, and the two metadata info tools add little practical value.
The domain of browser automation is well covered: navigation, page interaction, forms, uploads, dialogs, console, network requests, tabs, and snapshots are all present. Missing pieces like reload, forward navigation, and cookie/storage management are gaps, but agents can work around them using browser_navigate or browser_evaluate.
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