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

Adds substantial behavior beyond the annotations: a bounded 10-second wait, exactly one signed delivery, a preview flag, verification of the receiver's signature check, and the side effect that the test is written to the audit log. This tells the agent it is an outward-facing, non-idempotent, audit-visible action even though destructiveHint is false.

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 compact sentences, front-loaded with what is sent and where, followed by the timeout and side effects. No filler or redundancy; 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 2-parameter tool with full schema coverage and no output schema, the description covers the send, the 10s wait, and audit logging, but only vaguely says it will 'report what came back' without indicating the shape of the response (status, headers, body, signature verification result). Slightly more return detail would close the gap.

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 (revision, endpoint_key) are already fully documented in the schema, including the omit-to-use-active-revision and draft-testing semantics. The description adds no parameter-level detail beyond that, so the baseline of 3 is appropriate.

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 (test/send), resource (webhook endpoint delivery), and scope (a single signed test delivery to a revision's URL). It is clearly distinguishable from siblings like save_webhook_endpoint, activate_webhook_endpoint_revision, and rotate_webhook_endpoint_secret.

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 'test delivery' and the preview flag, but the description gives no explicit when-to-use or when-not-to-use guidance, and does not name alternatives (e.g. use save_webhook_endpoint to persist, activate_..._revision to promote). The revision-vs-active choice lives in the schema, not the description.

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