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

Adds substantial behavior beyond annotations: what is returned (hookId, private credentials, ownership challenge), the post-state (delivery remains inactive until verification), and a security constraint (keep recoveryKey secret). This complements the idempotentHint without contradicting it.

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 outcome is front-loaded in the first sentence, the workflow follows, and the recoveryKey caveat closes. Every clause carries operational information with no filler.

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?

With no output schema, the description compensates by describing the return payload and the inactive-delivery state, and it links the call to its required successor tool. Nothing needed to invoke or recover this tool 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 baseline is 3, but the description adds relational semantics the schema cannot: recoveryKey must be reused with the identical target and must not change across a retry. It does not add format detail, so it stops short of a 5.

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 ("Register an HTTPS receiver you control") and immediately distinguishes itself from the sibling verify_destination by naming the follow-up call. An agent can tell this is the registration/onboarding step, not the verification step.

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 explicit sequencing (publish the exact challenge on your origin, then call verify_destination) and an explicit anti-pattern (do not register again with a new key; reuse recoveryKey with the identical target after interruption). Both when-to-use and when-not-to-use are covered.

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