Play Chess Move

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

Annotations already mark destructiveHint=true, but the description adds critical concurrency behavior: the STALE_POSITION rejection if the revision is outdated. It also states it returns the resulting state, which is useful even with an output schema.

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?

Three concise sentences deliver the core action, uniqueness, and concurrency requirement with zero fluff. Each sentence earns its place.

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 mutating tool with an output schema and annotations, the description covers the essential operational details: mutation, concurrency control, error condition, and move format. It is complete enough for an agent to use 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?

With zero schema description coverage, the description compensates by explaining the 'move' parameter (SAN vs UCI) and the 'expected_revision' parameter (required, from a recent read, and its role in staleness). The 'game_id' is self-explanatory, so overall it adds substantial meaning.

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?

Description explicitly states 'Play a move' and even clarifies SAN/UCI formats. The unique claim 'This is the ONLY tool that mutates the game' clearly differentiates it from all siblings, which are read-only or other operations.

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 clearly states when to use this tool (to make a move) and specifies the required expected_revision from a prior read. It does not explicitly mention alternatives, but by highlighting it's the only mutating tool, it implicitly advises that all other tools are non-mutating.

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