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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety profile is covered. The description adds genuinely useful behavioral context: it discloses that PSA authentication notes (signing habits, forgery risk, signature evolution), biography, and a price guide are returned, and warns that item types vary by subject.

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 dense sentence front-loads the resource and its contents, then adds the id provenance. It is appropriately sized, though the long parenthetical list makes it slightly heavy.

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-value details need not be restated, and annotations cover the safety profile. The description supplies content scope and parameter provenance, leaving nothing critical for an agent to call it correctly.

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 0%, so the description must carry the burden for SubjectID. It does add meaningful provenance ('numeric id from a psa_autographfacts_subjects result'), which the bare string-typed schema lacks, though it gives no format examples.

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/resource ('One autograph subject's full public reference page') and enumerates the exact contents returned, distinguishing it from sibling tools like psa_autographfacts_subjects by naming the id source 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 establishes the dependency chain by stating the id comes 'from a psa_autographfacts_subjects result', which tells the agent the lookup flow. It does not, however, state any when-not conditions or alternatives.

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