browser_evaluate

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

Annotations already declare destructiveHint=true, openWorldHint=true, and readOnlyHint=false, covering the risk profile. The description adds the scope 'on page or element' but does not disclose additional behavioral details like potential DOM modifications, network requests, or permission prompts. Since annotations cover the main safety aspects, a midpoint score is appropriate.

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 sentence with no unnecessary words. It is concise and to the point, earning its place by stating the core functionality without fluff.

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?

Despite having a moderately complex execution tool, the description is overly terse. It does not mention how results are returned (text vs. file), the impact of providing target/element, or any caveats about running arbitrary JavaScript. The schema and annotations cover some details, but the description leaves significant gaps for an agent deciding how to invoke this tool safely and correctly.

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 input schema provides descriptions for all four parameters (target, element, filename, function), achieving 100% coverage. The tool description does not add any extra meaning beyond the schema, so it meets the baseline but does not exceed it.

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 verb 'Evaluate' and the resource 'JavaScript expression on page or element', giving a specific action and scope. However, it does not differentiate this tool from the sibling 'browser_run_code_unsafe', which also executes code, so it loses one point.

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 on when to use this tool versus alternatives like browser_run_code_unsafe or other browser interaction tools. It does not mention prerequisites such as needing a page snapshot for element targeting, nor does it explain when file saving vs. text return is appropriate.

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