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

The annotation already flags destructiveHint=true, so the safety profile is partly covered, and the description usefully adds the lapse/expiry rationale that motivates renewal. It does not, however, explain what makes this 'destructive' (e.g., whether renewal resets state or changes the expiry window) or disclose the side effects of the PUT.

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 tight sentences with the core action front-loaded, followed by the motivating rationale and the underlying endpoint. Zero filler; the endpoint reference is the only marginally non-essential element.

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 one-parameter mutation with annotations present and no output schema, the description covers the essentials. It still omits how far the expiry is extended, what the renewal returns, and any auth requirements, leaving the agent with gaps for a state-changing call.

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?

There is a single parameter with 100% schema description coverage, so the schema already documents subscription_id fully. The description adds no format, source, or retrieval guidance for the ID, 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 ('Extend a webhook subscription's expiry'), which is clearly distinct from the sibling operations create/delete/get/list. It is immediately clear what the tool does, though it doesn't explicitly name a sibling it must not be confused with.

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?

It gives usage context indirectly by explaining the consequence ('Oura subscriptions lapse if not renewed, so this is the tool that keeps a live integration alive'), which implies when to reach for it. However, there is no explicit when-not guidance, no mention of alternatives, and no prerequisites such as required auth scope.

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