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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds meaningful interpretive behavior beyond that: that registration alone is not evidence of an effect, that other_registry_entries flags non-trial links, that has_results means posted results, and the view=list paging ceiling of 100 rows. It does not cover rate limits or auth, but for a read-only search tool this is substantial added 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?

Front-loaded with the core action, then sibling routing, then role semantics, then caveats — a sensible order with little waste. It is dense and runs long, and the 'other_registry_entries signals their presence' sentence is slightly cryptic out of context, but no sentence is redundant.

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?

With 12 optional parameters, an output schema and rich annotations, the description supplies exactly the decision-level guidance an agent needs: sibling routing, default role behavior, what counts as a trial versus a mention, and result-status interpretation. Remaining details (sort enums, phase values, cursor mechanics) are fully documented in the schema and need not be repeated.

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%, so the baseline is 3, but the description goes further by explaining the default role=tests semantics, what measures/mentions actually mean in registry terms, and the list-view page limit. The role explanation in particular adds interpretive meaning (a measures link is not a trial of taking the peptide) that the schema's terse enum text does not convey as forcefully.

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 and resource (return registered clinical trials) and names the exact fields returned: registry status, phase, posted-results status and peptide role. It also names the two siblings it is not (search_findings, get_record), so an agent can route without opening any schema.

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?

Explicitly says when to use this tool versus search_findings (checked study results) and get_record (one full trial). It also spells out when to pick each role value and warns that role=measures/mentions return entries that 'are not trials of taking the peptide', which is the key selection nuance.

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