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 a genuine edge-case disclosure that the printed number is empty for sets PSA lists without one (e.g. autograph/player-only sets), which is useful behavioral context beyond the structured fields.

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 purpose, then the output edge case, then the parameter origin. Two sentences with little waste, though the parenthetical about empty numbers is slightly dense.

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 explanation is not required, and the description covers purpose, the single parameter's provenance, and one output caveat. It is adequate for a single-input lookup tool, missing only explicit sibling routing.

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 0%, so the description must carry the parameter meaning, and it does: it defines set_id as the numeric id sourced from a psa_cardfacts_sets result. This compensates for the undocumented schema field, though it stops short of 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 CardFacts set's full card checklist') and describes the returned content (every card's name and printed number). It implicitly distinguishes itself from the sets/categories siblings by tying set_id to a psa_cardfacts_sets result, though it does not explicitly name what it is not.

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?

It provides upstream context that set_id comes from a psa_cardfacts_sets result, which helps an agent chain calls correctly. However, it gives no explicit when-not-to-use guidance or alternatives, so usage is largely implied.

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