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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so safety is covered. The description adds real context beyond that: the auth prerequisite ('Needs a key') and the fields each record exposes, including last error, which tells the agent this is a debugging/inspection surface.

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?

A single efficient sentence with the resource and scope front-loaded and no filler. 'Needs a key' is terse to the point of mild ambiguity about which key, but it earns its place as an auth warning.

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?

With only two optional params and full schema coverage, the remaining burden is describing the result set, which the description does by enumerating the returned fields in lieu of an output schema. Ordering/retention semantics for 'recent' are unspecified, a minor gap for a read-only listing tool.

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 both parameters are already documented with types, ranges, defaults and examples. The description's 'for one endpoint, or all of yours' merely restates the id parameter's omit-for-all semantics rather than adding format or edge-case 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?

Names a specific resource (webhook deliveries) and states the returned attributes (status, attempts, last error, payload) plus the two scoping modes. It does not explicitly distinguish itself from siblings such as list_webhooks or test_webhook, so an agent must infer the routing.

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 implicit usage: pass an id for one endpoint, omit it for all of yours, and a key is required. There is no explicit when-not or named alternative (e.g., use test_webhook to send a test delivery), so selection guidance is only partial.

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