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

Annotations already declare readOnlyHint, openWorldHint, and destructiveHint=false, so the safety profile is covered. The description still adds genuine context the annotations do not: it explicitly rules out secrets in the response and states the call costs one API unit, plus the plan prerequisite. It stops short of describing pagination or ordering.

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 compact sentences, with the highest-value information (what is returned, and that secrets are excluded) front-loaded. 'API calls: 1' is terse but earns its place for budget-aware callers; no filler.

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 zero-parameter read tool with an output schema covering the return shape, the description supplies the essentials: contents, secret exclusion, and the plan prerequisite. Only the absence of any volume/pagination expectations keeps it from being complete.

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?

The tool takes zero parameters, so the baseline is 4 and there is nothing for the description to disambiguate. It correctly does not waste words on nonexistent inputs.

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?

Names a specific resource (this account's webhooks) and enumerates what is returned: failures, last success, last error, paused state. An agent can distinguish it from create_webhook or update_webhook, though it never explicitly contrasts with webhook_deliveries or list_webhook_events, which cover adjacent data.

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?

The prerequisite 'Needs a plan with webhooks' tells the agent when the call is viable, which is real guidance. However, it never says when to choose this tool over webhook_deliveries or list_webhook_events, so routing among the webhook-listing siblings is left to inference.

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