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

Annotations already cover idempotency and destructiveness. The description goes beyond them by explaining the multi-step process ('Step 1'), the exact return fields ('address, message_to_sign, expires_in_seconds, note'), the authentication requirement ('Needs your API key'), and that it is scoped to 'the account you are calling with.' This adds practical behavioral context, though it doesn't cover error/failure modes or session state, which is acceptable for a step in a larger workflow.

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?

Every sentence earn its place: purpose, use case, exclusions, return format, next step, auth requirement. No fluff or repetition. The information is front-loaded and structured so the critical facts (purpose and alternatives) come first, and the operational details follow. It's dense but readable.

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 two-parameter tool in a multi-step, overloaded nested environment, the description covers all necessary entry points: purpose, when to use, alternatives, output shape, next step, and authentication. It doesn't explain edge cases or expiration thresholds, but those are not needed for correct selection and invoicing. Given the absence of an output schema, the inline return-field list provides sufficient transparency.

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% for both parameters, so the base is 3. The description slightly augments the schema by describing the address as 'the agent's 0x wallet address' and the name as a label, but it doesn't explain validation rules or relational meaning. It adds no info beyond the schema for these parameters, so the baseline score is appropriate.

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 the tool is 'Step 1 of claiming an agent by its EVM address' and that it returns a SIWE message to sign. It explicitly distinguishes itself from computational siblings: 'Not for binding your own key (use bind_key_start) and not for plain key creation without a wallet (use create_api_key).' This makes the tool's purpose unambiguous and separates it from the two most likely alternatives.

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?

Provides explicit when-to-use guidance: 'Use it when an account owner wants a budgeted key for an agent that proves control of a wallet.' Also gives clear when-not-to-use instructions naming the exact alternatives, and even provides the next step ('Follow with claim_agent_complete'). The agent can decide correctly without extra inference.

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