execute_javascript

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

With no annotations, the description carries the full burden of behavioral disclosure, but it only states the action. It fails to mention side effects (e.g., page modifications), error behavior, return value format, security implications, or that script execution can navigate or alter the page. This is a significant transparency gap for arbitrary code execution.

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?

A single sentence that is front-loaded with the verb and resource, containing no filler or redundancy. It earns its place by stating the primary function immediately, maximizing conciseness and readability.

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 only 2 parameters and no output schema, the tool is inherently powerful (arbitrary JS execution) and requires warnings about side effects, return values, and error handling. The description offers no such context, making it inadequate for safe and effective use. The absence of output schema further amplifies this gap.

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 baseline is 3. The description adds no extra meaning beyond the schema; it neither clarifies parameter usage nor provides examples. The schema's own descriptions ('JS code to evaluate', 'Await the result if it's a Promise') are adequate, and the description does not need to compensate.

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 'Evaluate' and a clear resource 'JavaScript expression in the page context', making the tool's purpose unambiguous and distinct from sibling tools like navigate or click_element. It accurately communicates the core action without ambiguity.

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?

No guidance is provided on when to use this tool versus alternatives. The description does not mention situations where direct JS execution is preferred over debug_protocol or get_dom, nor does it state any exclusions or prerequisites, leaving the agent to infer usage from context alone.

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