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

Annotations already declare destructive/idempotent/not-readOnly, but the description goes well beyond them: cancels queued deliveries, in-flight HTTPS requests cannot be recalled, requires OAuth scope webhooks:write, and changes buyer or order state. Those are exactly the consequences an agent needs before an irreversible call.

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?

Front-loads the core effect and the queued-delivery cancellation, then layers qualifications. Three sentences, all carrying weight, though the density makes it read as a packed clause chain rather than tightly prioritized prose.

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 an output schema present, return values need not be explained, and annotations cover the safety profile. The description still supplies the auth scope, irreversibility caveat, and side effects on buyer/order state, leaving nothing an agent needs 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% and the single parameter is fully documented in the schema, including the pattern and the 'not a delivery ID or signing secret' warning. The description reinforces provenance (list_webhooks / create_webhook) but adds no new syntax or format detail, so the baseline of 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?

Specific verb+resource ('Stop future events for an owned subscription', 'revokes it and cancels queued deliveries') and it names the sibling tools that surface the required ID (list_webhooks, create_webhook). An agent can distinguish it from create_webhook and from any pause-like operation without further reading.

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?

States an explicit when-not ('This is not a pause') and routes the agent to create_webhook if a subscription is wanted again, plus it names where to obtain the subscription ID. It stops short of laying out a full decision rule (e.g. when to revoke vs. simply stop consuming deliveries), so it is clear context rather than complete guidance.

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