voidmail_set_webhook

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

Annotations declare destructiveHint=true, openWorldHint=true and idempotentHint=false, but the description adds real value beyond them: the refusal conditions and the owner-key auth requirement, plus the out-of-band owner endpoint. It does not, however, say what is destroyed (an existing webhook URL being replaced) or whether the generated secret is returned, which would fully justify a 5.

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 sentences, zero filler, and the purpose is front-loaded before the eligibility/refusal rule. Every clause carries information the agent needs.

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 two-parameter setter with no output schema, the description covers eligibility, refusal, and the fallback route well. The one gap is that it never states the effect on an existing webhook (overwrite/replace) despite destructiveHint=true.

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 'url' and 'secret' (including the 32-character HMAC signing detail) are already documented in the schema. The description adds no parameter-level information, 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 specific verb (Set) plus resource (webhook URL) and scopes it precisely to open-policy inboxes with no owner key. This is clearly distinguishable from siblings like voidmail_policy or voidmail_request_recipient without opening any 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?

Explicitly states the conditions under which the tool applies (open-policy inbox, no owner key) and the conditions under which it is refused (allowlist inbox, or any inbox with an owner key). It even names the alternative path for the refused case: POST /v1/agent-mail/owner/webhook with the owner key.

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