Create Webhook Subscription

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

Annotations already declare the write, non-idempotent, non-destructive profile, so the bar is lower; the description still adds real value by disclosing that the signing secret (whs_...) is returned and only displayed, and that OAuth tokens are denied by default. That is a security-relevant, non-obvious trait the schema does not carry. It does not mention rate limits or duplicate-URL behavior.

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?

Three short sentences, front-loaded with the action, then the return payload, then the auth caveat. No filler and every clause carries information.

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 creation tool with an output schema (which removes the need to explain return values further), the description covers the essential context: what is created, what is returned, and the auth default. It omits what happens on duplicate URLs or whether the whs_ secret can be retrieved later, minor gaps for this tool type.

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 all five parameters (url, events, address, description, contentScope) are documented in the schema with constraints and enums. The description adds no additional parameter meaning beyond that, so 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 specific verb+resource ('Create an outbound webhook subscription') that is unambiguous against the mail_webhook_list/delete/test/disable siblings. It does not explicitly name those siblings or contrast itself with them, so it stops short of a 5.

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?

No when-to-use or when-not-to-use guidance, and no routing to alternatives such as mail_webhook_test or mail_webhook_list. 'Deny-by-default for OAuth tokens' is a permission note rather than usage guidance, so the agent gets no help deciding when this tool is the right one.

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