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

With no annotations, the description carries full burden. It details deterministic one-shot retrieval, relay drainage, DM deletion for wrong phrases, NACKing, acceptance of first match, and the fallback 'courier_not_found' result. It also explains the credential_card path bypasses relay and that no server restart is needed. Minor omission: does not mention any error conditions beyond 'not found'.

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 moderately long but well-structured: purpose first, then flow, then details. Each sentence provides necessary information, though some redundancy exists (e.g., 'Deterministic, one-shot retrieval' is stated both in the flow and later). Still, it is efficient for the complexity.

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 the 4 parameters with 100% schema coverage and an output schema present, the description sufficiently covers the tool's behavior, constraints, and edge cases. It explains the two execution paths (relay-based and direct redemption) and the result for no match. Minor gap: no guidance on output format, but output schema handles that.

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 coverage is 100%, so baseline is 3. The description adds value by explaining 'dpop_token' as the session phrase from request_credential_channel and clarifying that 'credential_card' is optional and bypasses the relay drain, going beyond the schema's default descriptions.

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 picks up credentials from the Secure Courier and completes the CREDENTIAL-DELIVERY flow. It distinguishes itself from the sibling 'receive_npub_proof' by noting it is the ownership-proof counterpart, making the purpose specific and non-ambiguous.

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 says 'Call this only after the user confirms they have replied.' and warns against polling ('Do NOT poll, loop, or retry.'). It provides context for the flow and mentions the credential_card bypass path, but does not explicitly list alternatives for when not to use this tool, though the sibling reference helps.

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