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

Annotations already flag destructiveHint=true, idempotentHint=false and openWorldHint=true, but the description adds genuinely new behavior: the event is queued, delivered within about a minute, and carries sample data rather than the account's real transfers. That last point materially softens the destructive hint and is exactly the kind of context annotations cannot convey.

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?

Four short sentences, front-loaded with the action and payload scope, then timing, then eligibility. Every sentence contributes; the only minor cost is that the auth restriction arrives last rather than up front.

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?

An output schema exists, so return values need no explanation, and the description still covers timing, payload nature, endpoint state requirements, and where to verify the result. Nothing an agent needs to invoke this correctly is missing.

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 coverage is 100% with a single well-documented 'id' parameter, so the schema carries the load. The description adds no format or sourcing detail beyond it, which is the expected baseline here.

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 ('Queue one test event to a webhook endpoint') and immediately scopes the payload ('about a sample transfer and never one of the account's own'), which cleanly separates it from create_webhook_endpoint and list_webhook_deliveries.

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?

Gives clear preconditions: pending endpoints can receive tests, and only the account owner's API keys or connected apps may send them. It also routes the agent to 'read the endpoint's deliveries' for the outcome, though it does not name the sibling tool (list_webhook_deliveries) explicitly.

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