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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, so the safety profile is covered. The description adds 'Experimental source' (a reliability caveat) and the ClinicalTrials.gov cross-link behavior, but omits pagination, rate limits, or auth context.

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 front-loaded sentence packs verb, system, domain, both modes, and the cross-link note with no filler. No wasted sentences, though structure is dense rather than segmented.

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?

For a 7-param search tool with no output schema, the description covers identity and the dual mode but omits pagination behavior and any sense of result shape. Adequate but with clear gaps.

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 57%, and the description maps the key filters (condition, medicine, sponsor, text, EU CT number) to usage. However page and page_size are undocumented in both schema and description, so the description does not fully compensate for the coverage gap.

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?

States a specific verb (Search) and resource (EU Clinical Trials Information System / CTIS) and adds the dual mode (search vs. get-one-by-CT-number). The 'EU' scoping distinguishes it from the sibling search_clinical_trials, though no sibling is named 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 lists filter fields but gives no when-to-use or when-not-to-use guidance relative to siblings like search_clinical_trials or get_clinical_trial. 'Experimental source' is a caveat, not usage direction.

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