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camoufox-mcp

camoufox-mcp

by ccostello97
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
Local

browser_evaluate

Execute JavaScript expressions within the active page to read or modify content, automate interactions, or validate behavior.

Instructions

Evaluate JavaScript in the page context

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "expression": "<expression>"
    },
    "name": "browser_evaluate"
  }
}

Input Schema

NameRequiredDescriptionDefault
expressionYesJavaScript expression to evaluate

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

B3.1/5.0
Behavior2/5

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

No annotations exist, and the description does not disclose behavioral traits such as whether the evaluation is synchronous, what happens with errors, whether it can modify the DOM, or what the return value is. This is a risky gap for a tool that executes JavaScript.

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 short sentence, which is concise and front-loaded. However, it could be slightly more structured by including a brief note about output or behavior, but it avoids 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?

Given the tool's power (executing JavaScript), the description is incomplete. It lacks information about return values, error handling, security implications, and whether it's a read-only or mutation operation. The absence of an output schema increases the need for descriptive context.

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

Parameters3/5

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

The input schema already describes the 'expression' parameter as 'JavaScript expression to evaluate' with 100% coverage. The description adds no additional meaning beyond the schema, so the baseline score of 3 applies.

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

Purpose5/5

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

The description 'Evaluate JavaScript in the page context' clearly identifies the verb (evaluate) and resource (JavaScript in the page context). It is distinct from sibling tools like browser_click, browser_navigate, etc., which perform other browser actions.

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, the description does not mention that this tool runs arbitrary code, which differs from interactive tools like browser_type. 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.

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