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

With no annotations, the description carries full behavioral burden and delivers: one-shot deterministic semantics, channel-scoped draining, destructive side effects (wrong-phrase DMs deleted and sender NACK'd), the ACK/stop condition, the failure mode (courier_not_found), and a post-success side effect (payment processor client reinitialized, no restart needed). This is unusually rich disclosure.

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?

Front-loads the core action, then flow context, then the usage warning, then mechanics. Dense but every sentence carries information; a few parentheticals and the flow aside could be trimmed, which keeps it just short of ideal.

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-value documentation is not required, yet the description still surfaces the notable result (courier_not_found). Given the multi-step credential-delivery flow and destructive relay behavior, nothing an agent needs to call this correctly is missing.

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 the schema already documents each field, but the description adds real meaning: the (sender_npub, service, dpop_token) tuple identifies the response, credential_card redemption bypasses the relay and makes dpop_token unnecessary, and dpop_token is characterized as the session phrase from request_credential_channel. It clarifies inter-parameter relationships the schema treats only in isolation.

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?

States a specific verb+resource ('Pick up credentials from the Secure Courier') and names the exact flow it belongs to. It also explicitly distinguishes itself from its counterpart receive_npub_proof, so an agent can tell the two apart without opening either schema.

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?

Gives an explicit precondition ('Call this only after the user confirms they have replied'), names the predecessor tool request_credential_channel, and delivers a strong exclusion ('Do NOT poll, loop, or retry'). The alternative path (credential_card bypassing the relay) is also described with its own condition.

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