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

No annotations are provided, so the description carries full burden. It thoroughly discloses: the human-in-the-loop flow, that a welcome DM is sent, that the recipient must manually reply, that each receive_credentials call destructively drains the relay mailbox, and that polling/retrying is forbidden. This is comprehensive behavioral 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?

The description is efficiently structured: the main purpose is front-loaded, critical distinctions appear immediately after, and the human-in-the-loop imperative is clearly separated at the end. Every sentence earns its place with high information density.

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 tool with two parameters, no annotations, and an output schema present, the description is exceptionally complete. It covers purpose, usage boundaries, workflow, user interaction requirements, and destructive consumption behavior. Nothing essential is missing for an agent to correctly select and invoke this tool.

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%, so the schema already documents both parameters. The description adds context by mentioning service secrets and the credential template, but doesn't provide additional syntax or format details beyond the schema. Baseline 3 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 states a specific verb ('Open a Secure Courier channel') and resource ('credential delivery'), and immediately distinguishes this tool from request_npub_proof. It clearly identifies the intended use case: handing over service secrets (API keys, tokens) versus proving npub control.

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 when to use this tool (credential delivery flow) and when NOT to use it (for npub proof, use request_npub_proof; for dynamic/OAuth2 services, check service_status first). It also gives sequencing instructions: after calling, STOP, tell the user, wait for confirmation, then call receive_credentials. This is exemplary guidance.

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