browser_evaluate

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

The annotations already communicate destructiveHint=true and readOnlyHint=false, which cover the safety profile. The description adds that evaluation can target a page or element, but it does not disclose side effects, execution context, or whether arbitrary code can mutate page state. No contradiction with annotations exists.

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 front-loaded sentence with no filler or repetition. Every word contributes to identifying the operation, making it highly concise and easy to parse 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?

The schema covers parameters and the annotations cover destructiveness, so the core invocation is viable. However, there is no output schema, and the description does not explain return shapes, error behavior, execution context, or how this differs from running unsafe code. It is adequate but has clear gaps.

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 the schema already documents all four parameters. The description only loosely maps to function, target, and element without adding meaning beyond the schema. This matches the baseline for fully covered schemas.

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 uses a specific verb and resource: 'Evaluate JavaScript expression on page or element'. It clearly states what the tool does. However, it does not explicitly distinguish itself from the sibling browser_run_code_unsafe, which also appears to execute JavaScript, so it does not earn a 5.

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 about when to use this tool versus browser_run_code_unsafe or any other sibling. It does not mention situations where element targeting is required, nor when the filename parameter should be used instead of returned text. There is no when-to-use or when-not-to-use information.

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