eval_js

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

No annotations are provided, so the description carries full responsibility for disclosing behavior. It only mentions execution and returning a result, omitting potential side effects on the page, error handling, or the fact that arbitrary code can be run. This is a significant gap for a code execution tool.

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 redundant words. Every part contributes to the core purpose, making it highly concise and efficient.

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?

Although the tool has only one parameter, the description lacks critical behavioral details for safe and effective use by an agent. It does not mention the need for a loaded webview, possible page mutations, or how the result is serialized. The presence of an output schema does not compensate for missing usage context.

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 has a single parameter 'code' with no description, and schema description coverage is 0%. The description does not elaborate on what 'code' should contain, syntax expectations, or whether it accepts expressions vs. statements, so it adds no meaning beyond the schema.

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 executes JavaScript in the webview page and returns the result. It uses a specific verb ("Execute") and resource ("JavaScript in the webview page"), and it distinguishes from the sibling eval_python by naming JavaScript explicitly.

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 over alternatives such as eval_python or other DOM interaction tools. It does not mention prerequisites, exclusions, or recommended scenarios.

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