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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, but the description adds real operational context the annotations cannot: 7-day retention, API key plus paid-plan requirement, and zero credit cost. Retention and cost/auth prerequisites are exactly the kind of facts an agent needs before planning a 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?

Four short sentences, each carrying distinct payload: what is returned, when to use it, retention, and auth/cost. Front-loaded with the resource and ordering, with no filler or repetition.

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?

There is no output schema, yet the description enumerates the return fields (event, arrival status, attempt count, server response), so the agent knows what it will get. Combined with retention, auth, and cost notes, nothing needed 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 100% and both parameters (id, limit) are fully documented in the schema, including the 1-100 range and newest-first ordering. The description's 'one endpoint' and 'newest first' merely restate the schema, adding no new syntax or constraint detail, 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?

States a concrete verb+resource with scope and ordering: 'What we sent to one endpoint, newest first', then enumerates the fields returned (event, delivery status, attempt count, server response). This is unmistakably distinct from list_webhooks (endpoint configuration) and test_webhook (sending a test), so an agent can route to it without opening a 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?

'This is where to look when an event never showed up' gives an explicit diagnostic trigger for using the tool. It does not name alternative tools (e.g., test_webhook for proactive checks, list_webhooks for config) or state exclusions, so it falls short of the 5-level when/when-not/alternatives bar.

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