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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and openness are covered. The description usefully characterizes the return content ('captioned authenticated bat exemplars'), but adds no pagination, auth, or rate-limit 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?

Two tight sentences with the action and its input source front-loaded, then routing instructions. No wasted filler; the only minor redundancy is repeating the subject-ID sourcing in both sentences.

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 an output schema present, return values need no explanation, and the read-only annotation covers mutation risk. For a single-parameter lookup the description supplies what an agent needs: what it fetches and how to get the ID, though it omits any pagination or result-size expectations.

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 description coverage is 100% and the single parameter is already documented as a numeric subject id from a psa-probatfacts-subjects result. The description restates this provenance rather than adding new syntax or format guidance, so baseline 3 applies.

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 (Fetch) and resource (PSA's captioned authenticated bat exemplars), and ties the input to a named source tool. An agent can distinguish this from generic PSA lookups, though the 'captioned'/'bat' qualifiers are the main differentiator.

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 routes to siblings with conditions: psa_autographfacts_subject 'for autograph guidance' and psa_probatfacts_subjects 'to discover players'. This tells the agent how to obtain the required SubjectID, but there is no explicit statement of when this tool itself is the right one versus e.g. psa_probatfacts_subject.

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