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

With no annotations, the description carries the full behavioral burden and does so thoroughly. It discloses the deterministic one-shot behavior, relay-only drain, deletion/NACK of wrong DMs, ACK/stop on the first match, courier_not_found failure mode, direct credential_card redemption without relay access, and post-success reinitialization of the payment processor client.

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 every sentence earns its place: call timing, one-shot semantics, side effects, failure behavior, and the alternate redemption path are all operationally relevant. The key constraint is front-loaded with bold text and the structure makes the two paths easy to distinguish.

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 tool's complexity, the absence of annotations, and the presence of an output schema that handles return-value documentation, the description covers all essential context: preconditions, exact relay behavior, destructive side effects, failure result, alternative credential_card path, and post-success behavior. Nothing critical is left for the agent to guess.

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?

Although the schema already documents each parameter, the description adds meaning beyond it by grouping sender_npub, service, and dpop_token as the 'response you want' and clarifying that dpop_token is not required when a credential_card is provided. It also ties service to the value used in request_credential_channel, reinforcing schema intent.

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 operation: 'Pick up credentials from the Secure Courier' and identifies the flow it completes (CREDENTIAL-DELIVERY). It also explicitly distinguishes itself from the sibling tool receive_npub_proof, which is called the ownership-proof counterpart.

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 provides an explicit call condition: 'Call this only after the user confirms they have replied.' It also gives direct usage prohibitions ('Do NOT poll, loop, or retry'), names the alternative tool for ownership proofs, and explains when the credential_card path should be used instead of the relay-draining path.

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