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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new context beyond them: the signed-in session requirement (explicitly not an API key) and the default page size of 20. It stops short of ordering/pagination or failure-recording semantics, so it is strong but not exhaustive.

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 tight sentences, front-loaded with the trigger and the return payload, then auth constraint, then exclusion. The trailing ', 20 by default' is awkwardly spliced onto the field list and duplicates schema information, a minor structural blemish.

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 an output schema present, enumerated return fields are bonus rather than necessity, and annotations cover the safety profile. The auth prerequisite and the read-only boundary are disclosed, leaving only minor gaps such as how results behave when projectId is omitted.

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 `limit` and `projectId` are fully documented in the schema and the baseline is 3. The description repeats the default of 20 and never mentions the projectId scoping parameter, so it adds nothing the schema does not already carry.

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?

Opens with a specific trigger and verb+resource: reading CronCool webhook subscription configuration and recorded delivery failures. No sibling tool covers webhooks, so the scope is unambiguous, and the closing 'Not for changing or re-enabling a webhook' pins down the boundary further.

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 an explicit trigger ('Use this when the user wants to read...') and an explicit exclusion ('Not for changing or re-enabling a webhook'), which is exactly the when/when-not split an agent needs. No webhook-mutation sibling exists to name, so no routing is left ambiguous.

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