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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds substantive content context beyond the annotations: the page is public/non-commercial and deliberately excludes price data, which tells the agent what it will and will not find inside the payload.

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?

Roughly three sentences, each earning its place: content summary, sibling differentiation, and parameter sourcing. The scope statement is front-loaded and there is no filler.

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 single-parameter read tool with an output schema already describing the return shape, the description supplies everything else an agent needs: what the page contains, what it omits, and where the id comes from. Nothing material is missing.

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, and it does: it explains that subject_id is the numeric id obtained from a psa_probatfacts_subjects result, giving the agent a way to source a valid value. The only nit is the casing mismatch between the description's 'subject_id' and the schema's 'SubjectID'.

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 resource ('One player's full public reference page') and enumerates its contents (bat-authentication notes, professional models used, signature placement, biography). It also distinguishes itself from the sibling psa_autographfacts_subject by noting the absence of a price guide, so an agent can tell the two apart without opening schemas.

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 names the sibling alternative (psa_autographfacts_subject) and the differentiator (no price guide), and routes the agent to psa_probatfacts_subjects for obtaining the id. It stops short of an explicit 'use X when you need prices, use this when you need authentication notes' rule, so the choice is strongly implied rather than fully spelled out.

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