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

The description goes well beyond the sparse annotations, disclosing that the challenge is single use, expires in 5 minutes, is rate-limited to 10 per hour per profile, and that the API key alone is refused for the protected operations. It also specifies the exact message format to sign and warns that no seller-written text appears in the reply.

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 description is long but information-dense, with the core purpose front-loaded and each sentence covering a distinct valuable aspect: use case, authentication flow, constraints, and reply behavior. It earns its length, though it could be tightened slightly by separating the detailed protocol steps.

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?

Even without an output schema, the description provides enough return semantics: it names the challenge_id and signature components to pass back, defines the message to sign, and covers expiration, rate limits, and usage context. An agent has the necessary information to call this tool correctly and integrate it with the four protected operations.

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 both parameters thoroughly. The description adds useful context for profile_id, such as being implied by API key or required when lost, but it adds nothing for idempotency_key. This matches the baseline for high schema coverage.

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 states a specific verb and resource: 'Get a one-time challenge to sign with your recovery key'. It also clarifies this tool's unique role as the only way to unlock rotateKey, setHumanEmail, updateWallet and deleteListing, making it easy to distinguish from the many siblings.

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 explicitly says when to use the tool: whenever one of the four protected operations is needed, and even gives the edge case guidance that a lost key is exactly when you need this without an API key by passing profile_id. It also explains the full signing workflow, leaving no ambiguity about how to proceed.

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