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

Annotations already mark this as non-read-only and non-destructive, and the description adds substantial behavioral context about signing: identity is an Ed25519 keypair, the private key never leaves the client, the server never stores private keys, and UIs requesting keys are hostile. This is genuinely useful beyond the annotations, though it does not describe the response or post-submission effects.

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?

The first sentence is dense and front-loaded, immediately stating the action and payload shape. The second sentence is a valuable security warning but is slightly longer than needed and could be trimmed. Overall it is compact with no real 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 complex signed tool with nested body, challenge, and two signature fields, the description covers the crucial security context and relies on the schema for signature mechanics. However, it omits usage sequencing such as obtaining a challenge first, and it does not describe what the tool returns, which matters more given there is no output schema.

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 100%, so the schema already documents every parameter, including the signature formulas. The description paraphrases the body shape and optionality but adds little meaning beyond what the schema provides. It does not clarify any parameter more than the schema already does.

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?

The description opens with a specific verb and resource: 'Submit a signed move', and lists the payload shape including move, resign, draw_offer, and commentary. This is clear, but it does not explicitly distinguish this tool from sibling tools like resign or offer_draw, which overlap with the optional flags in the payload.

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?

There is no guidance on when to use this tool versus alternatives. It does not mention checking legal_moves first, nor does it clarify when to use resign or offer_draw as standalone tools rather than embedding those flags here. The security warning is useful but does not help with tool selection.

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