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

With no annotations provided, the description carries full burden. It discloses that the tool sends a welcome DM, requires manual human reply, is human-in-the-loop, and warns that each receive_credentials call destructively drains the relay mailbox. This adds significant behavioral context, though it could mention error handling or timeouts.

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 a clear front-loaded purpose, followed by usage guidance and behavioral notes. Each sentence adds value, though some detail (e.g., explicit 'do not poll') could be slightly shortened. Overall, it efficiently communicates the essential information.

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 and the absence of annotations, the description covers the flow, human-in-the-loop requirement, post-call actions, and warnings about destructive behavior. It could include what happens on error or timeout, but it is sufficiently complete for an agent to use correctly.

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 baseline is 3. The description adds no new semantic information beyond what the schema already provides for both parameters (service and sender_npub). It does not elaborate on formats or constraints.

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 opens a secure courier channel for credential delivery, distinguishing it from request_npub_proof and noting when not to use it (e.g., for OAuth2 services). The verb 'open' and resource 'credential channel' are specific and distinct from siblings.

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 advises when to use (credential delivery) and when not (for npub proof), references checking service_status first for dynamic services, and provides step-by-step post-call instructions: stop, tell user, wait for confirmation, avoid polling. This is comprehensive guidance.

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