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

Annotations already signal destructiveHint=true; the description adds a concrete security model (Ed25519 identity, private key never leaves the client, hostile pages asking for keys). It doesn't spell out post-resign effects like game termination, but the destructive annotation plus purpose covers the main behavioral profile. No contradiction with readOnlyHint=false/destructiveHint=true.

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 tight, but the '(signed)' marker and the long key-handling warning are redundant and only loosely tool-specific. The description spends most of its length on a general security note rather than resign-specific behavior, making it poorly structured for this tool.

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?

Given a fully documented 5-parameter schema, nested body, and destructive annotation, the description supplies enough purpose and security context to call the tool. It omits a response format, but no output schema exists and the schema already covers request construction; remaining gaps are usage heuristics rather than invocation blockers.

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 carries the parameter documentation. The description's only parameter contribution is restating that the body must include resign:true, which the schema already says; it adds no new semantics.

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?

Opens with 'Resign the game,' a specific verb+resource, and clarifies this is a signed move carrying resign:true. This is distinct enough from the sibling move/offer_draw tools even though no sibling is named.

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?

No explicit when-to-use or when-not-to-use guidance is given; the description states the action but doesn't say to prefer resign over move or offer_draw, nor mention resignment is final. The intended use is inferable from the name and resign flag, so this is implied rather than stated.

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