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

Adds substantial context beyond the annotations (readOnly=false, idempotent=false): the signingSecret is returned only once and cannot be retrieved again, and there are environment and tier ceilings (Sandbox unsupported, Build=10, Scale=50). These are exactly the operational facts an agent needs and cannot get from structured fields.

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 tightly packed sentences: purpose first, then the critical one-time-secret warning, then limits. No filler, and the highest-risk information (store the secret immediately) is given prominent placement.

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?

An output schema exists, so return structure need not be described, yet the description still flags the one non-obvious return detail (one-time signingSecret). Combined with the availability and quota constraints, nothing material is missing 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%, so the schema already documents url, name, and eventTypes with examples and validation rules. The description adds no parameter-level detail, so the baseline of 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?

States a specific verb and resource ('Registers a webhook endpoint'), which cleanly separates it from delete_webhook, get_webhook, list_webhooks, and update_webhook siblings. It doesn't explicitly name an alternative, but the create action is unmistakable.

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?

Usage is implied by the create semantics and the availability constraint ('Not available on Sandbox'), which usefully tells the agent when the call will fail. However, there is no explicit when-to-use-vs-alternative guidance connecting it to update_webhook or the listing tools.

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