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

The description adds valuable behavioral context beyond the annotations: the challenge is short-lived, the operation is public, and it creates no payment. Annotations are neutral (all false), and the description does not contradict them. It does not disclose failure modes or expiration handling, but the 'short-lived' and 'exact message' details are helpful.

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 two sentences, no fluff. It front-loads the core purpose and then adds critical procedural context. Every word 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?

An output schema exists, so return values are covered. The description covers the essential flow (create challenge, sign, complete via sibling) and important constraints (short-lived, public, no payment). It does not mention optional params or the HTTPS callback requirement, but the schema already documents those. Overall, it is sufficiently complete for a first-step tool.

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 50% (3 of 6 params have descriptions). The description adds no parameter-specific semantics beyond referencing 'Base wallet', which aligns with the walletAddress schema. It does not compensate for the undocumented optional parameters (label, clientName, clientVersion), leaving gaps in understanding.

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 clearly states a specific action ('Create a short-lived EIP-4361 challenge') targeting a specific resource ('Base wallet'). It distinguishes this from the sibling tool complete_agent_registration by framing it as the first step in a two-step flow, making the purpose unambiguous.

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?

The description explicitly provides a usage sequence: 'Sign the exact returned message, then call complete_agent_registration.' It also clarifies public access requirements (no payment, no Google/email). It does not mention explicit alternatives or when-not-to-use scenarios, but the sequential context is strong enough for an agent to know when to invoke it.

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