browser_eval

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

No annotations are provided, so the description carries the full burden. It discloses two key behaviors: the confirmation prompt on non-local pages and the JSON-serializable return. This is meaningful context beyond the schema, though it does not elaborate on side effects or error handling.

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 two concise sentences, front-loaded with the action and result. Every clause adds value: what it does, what it returns, and an important behavioral caveat. 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?

Given the tool is a single-parameter JavaScript evaluator with no output schema, the description covers the core purpose, return type, and a key situational behavior. It lacks details on asynchronous expressions or non-serializable results, but these are secondary for a minimal 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?

The schema has one parameter with no description (0% coverage). The description explains that 'expression' is a JavaScript expression and that its result must be JSON-serializable. This directly compensates for the missing schema description, though it does not provide examples or syntax details.

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 evaluates a JavaScript expression in the page context, which is a specific verb+resource. This distinguishes it from sibling tools that navigate, click, or read the DOM. The scope and return behavior are explicitly mentioned.

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 for running custom JavaScript in the page, but it does not explicitly contrast with alternatives or provide when/when-not guidance. The note about prompting on non-local pages hints at a prerequisite but no explicit alternatives are named.

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