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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds the useful content disclosure (biography, auth notes, price guide), but says nothing about rate limits, caching, or freshness behavior beyond what the schema conveys. With annotations carrying the safety bar, a 3 is appropriate.

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 zero waste. The purpose and returned fields are front-loaded, and the routing guidance follows without padding.

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 not be explained, and the description still names the returned fields. Parameter and annotations are complete; only minor behavioral details (freshness, pagination) are absent, which is acceptable for a single-id detail tool.

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% — the single SubjectID parameter is documented as a numeric id from a subjects result. The description implies the id source but adds no syntax or format detail beyond the schema, so the baseline 3 holds.

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 (one PSA AutographFacts subject), and enumerates the exact payload: authentication notes, biography, and item-type price guide. This clearly distinguishes it from the plural subjects list and the gallery tool.

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 the agent: use psa_autographfacts_subjects to obtain the SubjectID and psa_autographfacts_gallery for authenticated exemplars. Both alternatives and their selecting conditions are named, leaving nothing to inference.

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