Browser Instrumentation MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively describes key behaviors: it requires session escalation (a critical prerequisite), executes JavaScript (implying mutation), and returns observed changes rather than success/failure (clarifying output behavior). However, it doesn't mention potential risks like script errors or side effects.

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 well-structured and front-loaded with the core purpose, followed by prerequisites, args, and returns sections. Every sentence earns its place by providing essential information without redundancy, making it efficient and 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?

Given the tool's complexity (JavaScript execution with prerequisites) and no annotations, the description does well by covering purpose, prerequisites, parameters, and output behavior. The output schema exists, so return values needn't be explained in detail. However, it could mention error handling or security implications for a more complete picture.

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 0%, so the description must compensate. It adds meaningful context for all three parameters: 'session' is clarified as a browser session name, 'script' as JavaScript code, and 'reason' as a justification. This goes beyond the bare schema, though it doesn't specify format details like script syntax.

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 specific action ('Execute JavaScript') and the context ('in the browser context'), distinguishing it from sibling tools like browser_act_click or browser_act_type which perform different browser actions. It uses precise language that goes beyond a tautology.

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 explicitly states when to use this tool ('REQUIRES: Session must be escalated first via browser_session_escalate'), providing clear prerequisites and distinguishing it from tools that don't require escalation. It also implies usage context by specifying it's for JavaScript execution in a browser.

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