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

Annotations already mark this destructive and non-read-only, and the description goes well beyond them: it specifies that existing subscriptions break immediately with 404, that the call runs propose->confirm, that the response is status='confirmation_required' with an action_id and plan_token, and that the write only happens via confirm_action. That is exactly the behavioral context an agent needs before invoking a destructive rotation.

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-loaded with the action and effect in the first sentence, then the use case, then the confirmation mechanics. The all-caps emphasis and the confirmation block add length but each sentence carries distinct operational information, so little is wasted.

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 compensates by declaring the return shape ({ feed_url }) and the intermediary confirmation payload. For a zero-parameter destructive tool, nothing an agent needs in order to call it and handle the result 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?

The tool takes zero parameters, so the baseline is 4 and there is no parameter meaning to add. The description correctly does not invent inputs, only clarifying the return value.

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?

"Rotate (reissue) the caller's ICS calendar subscribe token" names a specific verb and resource, and immediately states the effect: the previous URL is invalidated and a fresh one returned. That distinguishes it from a read-only sibling like get_calendar_feed_url without needing to name it.

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 an explicit trigger — "Use this to REVOKE a subscribe URL that was shared or leaked" — with the consequence spelled out (old subscriptions immediately 404). It stops short of stating when not to use it or naming the read-only alternative for merely viewing the current URL, so it is strong but not fully comparative.

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