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

Adds real behavioral context beyond the annotations: Oura verifies the callback URL before activation, and the created subscription expires and must be renewed. These are non-obvious lifecycle facts an agent needs. It does not explain why destructiveHint=true or what state is created, but the annotations carry the safety profile and the description adds meaningful process detail.

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 tight sentences, front-loaded with the primary action, followed by the two operational caveats (verification, expiry) and the endpoint. Every sentence earns its place with 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?

With no output schema, the description should ideally note what the agent gets back (e.g., a subscription id needed later by renew/delete), which it omits. Otherwise it covers activation flow and expiry adequately for a 4-parameter, all-required creation tool.

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%, with each of the four parameters (callback_url, verification_token, event_type, data_type) already documented and an enum on event_type. The description adds no syntax or format detail beyond the schema, 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?

States a specific verb and resource ('Register a webhook so Oura notifies your callback URL when data changes'), clearly distinct from the sibling renew/delete/get/list subscription tools. The underlying endpoint (POST /v2/webhook/subscription) reinforces exactly what is being created.

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?

Explicitly names the alternative and lifecycle step: 'the subscription EXPIRES — renew it with oura_renew_webhook_subscription', which routes the agent to the correct sibling for the follow-up action. It lacks explicit when-not-to-use guidance (e.g., don't re-create an existing subscription), so it stops short of a 5.

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