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

Adds substantial context beyond the annotations: a 24-hour lifetime, the fact that signingSecret is returned only once, and that it consumes 1 API call. It stops short of describing what happens to stored requests after the 24 hours expire, so it is not fully complete.

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?

Four dense sentences, front-loaded with the core purpose before plan details and the one-time secret caveat. The trailing 'API calls: 1.' is terse but does carry cost information, so little is wasted.

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?

For a zero-required-param creation tool with an output schema, the definition covers lifetime, cost, plan behavior, and the one-time secret well enough to call correctly. The only gap is the post-expiry lifecycle of stored requests.

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?

Only one optional parameter exists and the schema documents it at 100% coverage ('Optional label'), so the description need not compensate. The baseline of 4 applies since no parameter information is required beyond the schema.

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 ('Create a hosted temporary URL that stores webhook requests') plus the distinguishing constraint ('no server or tunnel is needed'), which separates it from the sibling create_webhook that presumably targets an existing endpoint. An agent can pick between them 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?

Explains plan-based usage (works on every plan) and routes agents to the right follow-up: send_inbox_sample on Free/Starter, pointing a real webhook at the url on Pro/Scale. It gives clear context but never explicitly states when to prefer this over create_webhook.

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