evaluate_script

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 only mentions 'in a window realm' and 'active (or specified) context', but does not describe side effects, error handling, return value behavior, or safety implications. For a tool that evaluates arbitrary JavaScript, this is insufficient.

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, concise sentence that front-loads the core purpose. However, it omits important details like parameter usage and behavioral notes, so it sacrifices completeness for brevity.

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 (evaluating arbitrary JavaScript) and the lack of annotations, output schema, and parameter descriptions, the description is far from complete. It does not address return values, error handling, security concerns, or how to use the optional parameters. A more thorough description is needed.

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, but it adds no explanation for any of the four parameters (expression, awaitPromise, contextId, realmId). The parameter names are self-explanatory to some extent, but the description does not clarify their expected values, default behavior, or how they interact.

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 action ('Evaluate a JS expression') and the context ('in a window realm of the active (or specified) context'). It provides a specific verb and resource, but does not differentiate from the sibling tool 'evaluate_on_callframe', which likely evaluates in a call frame rather than a window realm.

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 explicit guidance on when to use this tool versus alternatives. The description implies it works with the active or specified context, but does not explain when to choose this over evaluate_on_callframe or other evaluation tools. No exclusions or prerequisites are mentioned.

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