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

Annotations already declare readOnlyHint=false, openWorldHint=true, idempotentHint=false, and destructiveHint=false, lowering the bar. Beyond that, the description adds genuinely important behavior: the signing secret is shown only once, which tells the agent to capture it immediately. It omits where the secret appears in the response and whether delivery retries occur.

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 short sentences, zero waste. The core action is front-loaded and the one-time-secret warning immediately follows.

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 fully documented parameters and no output schema, the description covers the essentials plus the one non-obvious return behavior (the one-time secret). It would be stronger if it clarified how this differs from org_webhook_create or that no delivery is attempted until an event fires.

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 (url and eventTypes with its mail.received default) are already documented in the schema. The description adds nothing about parameter format or constraints beyond what structured fields provide, 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 and resource: 'Registers an HTTPS URL' to receive notifications when mail arrives. Clear enough for an agent to know this creates a webhook endpoint. It does not distinguish itself from the sibling org_webhook_create, leaving scope ambiguity between the two.

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?

Usage is implied by 'to be notified when mail arrives', which tells the agent the trigger context. But there is no explicit when-to-use guidance, no mention of the org_webhook_create alternative, and no note on prerequisites such as a verified domain.

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