Create Webhook Subscription

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

Annotations already mark this as non-read-only, so the mutation is known; the description adds value with the signing secret return behavior and the OAuth deny-by-default constraint. It does not describe all side effects, but openWorldHint and schema cover much of the remaining context.

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?

Two tight sentences: the first states the core purpose, the second discloses output and access behavior. 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?

The schema and output schema cover parameters and returns, while the description adds the auth caveat and signing secret. It is sufficiently complete for an agent to invoke the tool correctly, though it could briefly note the admin-only preview restriction.

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 parameters are already fully documented. The description adds no parameter-level detail beyond that, which is acceptable given the baseline for full schema coverage.

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 action ('Create an outbound webhook subscription') with the resource type and unique return value (subscription metadata + signing secret). This clearly distinguishes it from sibling webhook tools like mail_webhook_list, mail_webhook_delete, and mail_webhook_test.

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?

The verb 'Create' plus the tool name make the intended use obvious among the siblings. It also gives an important exclusion ('Deny-by-default for OAuth tokens'), though it does not explicitly name alternatives or contrast with other notification approaches.

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