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Browser MCP

Browser MCP

by Agent360dk
OverviewSchemaSourceRelated ServersDiscussionsAdmin
JavaScript
Local

browser_screenshot

Take a screenshot of the visible area of the current tab. Returns base64 PNG, or saves to disk if path is provided. The image is in device pixels; when Chrome reports them in time, the answer also gives the CSS viewport size and…

Instructions

Take a screenshot of the visible area of the current tab. Returns base64 PNG, or saves to disk if path is provided. The image is in device pixels; when Chrome reports them in time, the answer also gives the CSS viewport size and devicePixelRatio, which browser_click_xy coordinates need. Chrome stays where it is: if its window is covered by other windows, there is no picture and the answer is error "window-covered".

Input Schema

NameRequiredDescriptionDefault
pathNoFile path to save the screenshot to (e.g. /path/to/screenshot.png)
bring_to_frontNoRaise Chrome in front of the user if its window is covered, and leave it there. Takes the user's screen: only after the user agreed (browser_ask_user). Default false.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changedv1.30.2
    • addedInput schema / properties / bring_to_front
      Added value: +{
+  "description": "Raise Chrome in front of the user if its window is covered, and leave it there. Takes the user's screen: only after the user agreed (browser_ask_user). Default false.",
+  "type": "boolean"
+}
  2. First observedv1.0.0

TDQS

A4.3/5.0
Behavior5/5

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

With no annotations, the description carries the full burden and does so well: it discloses the return format (base64 PNG or file on disk), the pixel semantics (device pixels), the conditional viewport/dPR extras, and a concrete failure mode with its error string ('window-covered'). It also states a side-effect constraint (Chrome stays where it is).

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

Conciseness4/5

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

Front-loads the core action, then layers return format, coordinate caveat, and error case. Dense but every clause contributes; only the window-covered wording is slightly verbose.

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?

No output schema exists, so the description must explain returns, which it does (base64 PNG / file, viewport size + dPR). Error behavior and side effects are covered; edge cases like image dimensions or timing are left implicit but not critical.

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 both parameters are already documented, including the user-consent caveat on bring_to_front. The description adds only the consequence of path ('saves to disk') and the coordinate relevance of the output; it does not meaningfully extend parameter semantics, 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?

States a specific verb and resource ('Take a screenshot of the visible area of the current tab') with a clearly scoped target (visible area, current tab). No sibling tool does screenshots, so it is trivially distinguishable.

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

Usage Guidelines4/5

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

It ties the tool to downstream use ('devicePixelRatio, which browser_click_xy coordinates need') and to the prerequisite for bring_to_front ('only after the user agreed (browser_ask_user)'), giving clear contextual guidance. It stops short of stating explicit when-not conditions or alternatives.

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

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