validate

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

With no annotations provided, the description carries the full burden. It explains that structural and semantic errors are detected and returned 'path-pointed', and that 'isError' indicates invalidity. However, it does not mention if the tool is read-only, any side effects, or authentication needs.

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 two sentences with no extraneous content. The first sentence states the core function, the second details types of errors found. It is efficiently front-loaded.

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 no output schema, the description should clarify the return structure more fully. It mentions 'path-pointed' errors and 'isError', but does not specify the actual response format or fields. For a simple single-parameter tool, it is adequate but not complete.

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 already describes the parameter as 'The UI description: a fenestra/1 JSON object.' The description adds value by explaining what validation entails (structural and semantic checks), going beyond the schema's minimal description.

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 validates a 'fenestra/1' description, specifying the action and the resource. It also distinguishes itself by noting 'without rendering', contrasting with siblings like 'render_ui'.

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 implies use when validation without rendering is needed, but does not explicitly state when it should be used over siblings like 'check_a11y' or 'check_layout'. No exclusions or alternatives are given.

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