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

Annotations contain only the title, so the description carries the behavioral burden. It does disclose payment requirements and the HTTP equivalent, which gives some context about authentication and cost. However, it does not mention error behavior, rate limits, or whether the operation is purely read-only (though 'search' implies it). The added context is useful but minimal.

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 concise, with three short sections: the main purpose, the HTTP equivalent, and payment instructions. It is front-loaded with the core purpose. The payment details are somewhat verbose but necessary for a paid API. Overall, it is efficient without redundancy.

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?

The description provides essential operational details like payment and headers, but it omits the response format, possible error conditions, or any usage examples. For a simple search tool with no output schema, the agent lacks crucial information about what to expect in the return payload. The description is adequate but leaves gaps for a tool that has no structured annotations or output schema.

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 is empty, but the description lists two optional parameters `q` and `page_size` with types. This adds some meaning beyond the schema, but it does not explain what these parameters represent (e.g., query text, pagination size). Since the description is the only source of parameter information, it could provide more semantic detail, but the types alone offer basic guidance.

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 it is a 'ClinicalTrials.gov search' – a specific verb ('search') and a specific resource ('ClinicalTrials.gov'), which immediately distinguishes it from general web search or other domain-specific search tools. It is unambiguous and non-tautological.

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 explicit guidance on when to use this tool versus alternatives. It only gives the endpoint and payment details, leaving the agent to infer from the name and source that it is for clinical trial queries. There is no mention of use cases, exclusions, or comparisons to sibling search tools.

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