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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds useful context beyond those hints: scale of coverage, worldwide scope, the ClinicalTrials.gov source, and the fields returned. There is no contradiction with the annotations.

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 tight sentence front-loads the action and packs scope, filters, return fields, and data source with no filler. Every clause earns its place.

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 is complete for a read-only search tool: it states what it searches, how to filter, what it returns, and the authoritative source. The rich schema and output schema already cover pagination, limits, and return formatting, so no critical invocation detail is missing.

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 coverage is 100% with detailed descriptions for all 8 parameters, so the baseline is 3. The description repeats some parameter semantics with examples (condition, intervention, status, phase) but does not add meaning beyond what the schema already provides.

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 verb and resource: 'Search 577,000+ clinical trials worldwide' and lists the filters and return fields. It is clear and specific, but it does not explicitly differentiate itself from siblings like health.clinical.study or health.clinical.stats, so it stops short of a 5.

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 usage through the search/filter framing and provides concrete example filter values, so an agent can infer when to call it. However, it never mentions when to prefer an alternative such as health.clinical.study for trial details or health.clinical.stats for aggregate counts, leaving the comparison to the agent.

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