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

Adds substantial context beyond the annotations: the return is a 90-day listing-control credential, retries are idempotent in a specific way (the grant is recovered), and a new proof revokes prior credentials. It also bounds scope negatively ('does not approve branding or change grades', 'never signs payments'), which is exactly the kind of side-effect disclosure a mutation tool needs.

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?

Five short sentences, front-loaded with the action and its precondition, followed by return value, idempotency, side effects, and negative scope. No sentence is filler; each carries a distinct fact an agent needs.

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 covers the return value, its lifetime, retry behavior, destructive side effects on prior credentials, and explicit non-effects. Nothing an agent needs in order to invoke 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 description coverage is 0%, so the description must carry the semantic load. It adds real meaning for requester_key ('the same private requester key', i.e. must match the start call) and situates challenge_id as a one-hour domain challenge, but adds nothing about formats or failure conditions for either parameter.

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 and resource ('Confirm a one-hour domain challenge') with the key constraint that makes it work. The verb naturally distinguishes it from the sibling start_ownership_proof, but the description never names that sibling explicitly, so the differentiation is implicit rather than stated.

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 clear operating context: the requester key must be the same private key, and the HTTPS origin and path must match exactly. The retry semantics ('identical retries recover that grant') clarify re-invocation behavior. It does not explicitly state the prerequisite call (start_ownership_proof) or name alternatives, so it stops short of a 5.

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