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

With no annotations, the description fully details behavior: deterministic one-shot retrieval, draining only the rendezvous relay, deleting wrong DMs, accepting the first match, and returning 'courier_not_found' if none match. It also describes the alternative credential_card path. However, it doesn't explicitly state that messages are deleted (a destructive side effect), which would earn a 5.

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 well-structured with paragraphs and bullet points, front-loading the main purpose. Every sentence adds value, though the detailed drain process could be slightly more concise. Overall, it is efficient and clear.

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 (4 parameters, side effects) and the presence of an output schema (not shown), the description covers the flow, conditional paths, and result types. It mentions 'courier_not_found' and the reinitialization of the payment processor on success. It is complete enough for an agent to understand the tool's full behavior.

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?

The input schema has 100% coverage, so the baseline is 3. The description adds meaning: it explains dpop_token as the 'session phrase' from request_credential_channel, clarifies that credential_card bypasses the relay drain, and notes that service must match the earlier request. This extra context justifies a 4.

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's purpose: 'Pick up credentials from the Secure Courier' and completes the CREDENTIAL-DELIVERY flow. It differentiates from the sibling 'receive_npub_proof' by mentioning it as the ownership-proof counterpart, making the tool's role distinct.

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 instructs when to call: 'Call this only after the user confirms they have replied.' It also warns against polling, looping, or retrying. While it doesn't explicitly compare to sibling alternatives beyond the counterpart mention, the guidance is clear and actionable.

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