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

Despite metadata annotations indicating destructiveness, the description adds valuable behavioral context: the signing secret is returned only once, and it explains the exact signature verification format. It also notes the owner/admin permission, which is beyond what annotations provide. No contradiction with annotations is present.

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?

Two sentences with no fluff. The primary purpose is stated first, followed by crucial security details and permission context. Every clause delivers specific information, making it efficient and easy to parse.

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 has an output schema (not shown) and annotations, the description covers all critical operational aspects: what events are delivered, how the signature is verified, and the one-time secret exposure. It does not explicitly mention potential side effects (e.g., overwriting an existing webhook), but this is partly covered by the destructiveHint annotation. Overall, it is complete for correct invocation.

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% and both parameters are well-documented in the schema itself (url and events with defaults and enums). The tool description only adds a minor clarification (https requirement) and does not meaningfully compensate for any schema gaps, so the baseline 3 applies.

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 ('Register'), a specific resource ('an https URL'), and the exact purpose: receiving job lifecycle events via HMAC-signed POSTs, explicitly contrasting with polling. It clearly distinguishes itself from siblings like webhooks_delete and webhooks_list by describing the action of registration.

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?

It implicitly communicates when to use this tool ('push instead of polling') and mentions the permission requirement ('Requires owner/admin'). It does not explicitly state when not to use it or name alternatives, but the context is clear enough for an agent to decide between setting a webhook and polling.

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