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

Beyond the annotations, the description explains that cancellation is only a request requiring iPhone processing, that removal can happen during refresh or by opening the Planned workouts screen, that HealthKit results are not deleted, and that cancel_requested is not confirmation of removal. These details materially improve correct agent use and align with idempotentHint and destructiveHint.

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?

The description is dense but well front-loaded: purpose first, then processing caveats, then workflow guidance. Every sentence adds operational or behavioral value without redundancy.

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 cancellation tool with an output schema, the description covers the important behavioral caveats: asynchronous processing, HealthKit safety, confirmation semantics, idempotency, and the correct workflow for changing a plan. The remaining omission, where to get the id, is minor and partly covered by the single-parameter schema and sibling workout_plans.

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?

With only one required id parameter and 0% schema description coverage, the description adds some meaning by indicating the id refers to the user's identified workout plan. However, it does not clarify where to obtain that id or explicitly connect it to workout_plans, so the parameter guidance remains minimal.

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?

The description states a specific verb and resource: request cancellation of the identified workout plan. It also distinguishes the operation from changing a prescription by directing cancellation plus creation of a new plan, so an agent can tell it apart from create_workout_plan and workout_plans.

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 clear context for when cancellation is appropriate and explicitly names the alternative workflow for changing a prescription: cancel the old plan and create a new one for review. It does not provide explicit when-not guidance or point to workout_plans as the likely source of the plan id.

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