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

Annotations only give readOnly=false, idempotent=true, destructive=false. The description goes well beyond them: it discloses the side effect (re-sends the signed webhook.verify challenge), the state transition (flips pending → active IN PLACE), and crucially that id and secret are preserved rather than regenerated, which is the main thing an agent would otherwise have to guess about a mutating verification call.

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?

Three dense sentences, front-loaded with the precondition before the action and the state effect. The return-shape note is short and the already-active edge case is stated in the same sentence, so nothing reads as padding despite the 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?

A mutating, idempotent webhook tool with one required param and a full output schema. The description covers the precondition, the fix-and-retry workflow, the in-place semantics, the preserved credentials, and the no-op case — everything an agent needs to call it correctly at the right moment.

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?

There is a single parameter, webhookId, and schema description coverage is 100%, so the schema already documents it. The description does not add format or sourcing guidance for the id (it references data.token and verification.reason, but those are webhook fields, not this tool's parameter). 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?

States a specific verb+resource ('re-run ownership verification on a PENDING webhook') and immediately distinguishes it from create_webhook/update_webhook by scoping it to webhooks stuck in a pending state. The parenthetical reason codes (token_not_echoed / non_2xx_<code> / unreachable / ssrf_blocked) pin down exactly which objects qualify, so an agent can select it without opening the 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 ('one whose endpoint did not echo the challenge at create time') and an explicit trigger for the call ('After you fix the receiver to reply 2xx echoing data.token, call this'). It also rules out the delete/recreate alternative ('id + secret preserved — no delete/recreate') and documents the no-op case ('already-active webhook returns active unchanged').

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