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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds the substantive behavioral detail the annotations cannot: the shape of the result (ECO code, variation name, theory-departure move), which matters since there is no output schema. It stops short of noting behavior for unknown or transposed openings.

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?

One sentence, front-loaded with what is returned, no filler or repetition of the title. Every clause carries information.

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 one-parameter read-only tool with rich annotations, the definition covers input flexibility and both outputs, so an agent can call it confidently. Minor gaps remain around edge cases (insufficient moves, unlisted openings) which would be cheap to add.

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 100% and the single parameter already documents SAN notation and PGN acceptance with an example. The description's "list of moves or a PGN" mirrors rather than extends the schema, 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?

Specific verb ("Name") plus resource (the opening, ECO code and variation) and it also states the secondary output, the move where the game left named theory. This is far more informative than the bare name and lets an agent distinguish it from a general guide-style sibling.

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?

Usage is implied by the input: you supply a move list or PGN and get an identification back. There is no explicit when-to-use versus alternatives such as opening_guide, and no stated exclusions or prerequisites (e.g. minimum number of moves required).

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