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

Adds a genuinely useful protection rule beyond the annotations: copies the trainer individually customized are skipped. However, it omits the overwrite semantics (listed fields on student copies are replaced, not merged), whether the call is idempotent, how many students are affected, and what happens with partially customized copies. Annotations cover the safety profile reasonably (mutating, non-destructive, open-world).

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 main action first and the exception second; nothing is padded. The second sentence is slightly awkwardly phrased ('Copies the trainer customized...'), which costs a little clarity but no length.

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 two-parameter bulk mutation with no output schema, the description should say what the agent gets back (counts, failures) and whether some students can be skipped silently. It covers the core selective-copy and custom-preservation rules but leaves the outcome contract unspecified.

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 50%: workoutId is documented in the schema, `fields` is not. The phrase 'chosen fields' links the array to selective propagation, which is a small value-add over the enum list, but it does not explain that unlisted fields are untouched or how nested values like exercises are handled.

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 (copies selected fields) and resource (template workout → student copies), which is meaningfully distinct from update_workout and publish_workout. It never names those siblings, so an agent must infer from the name alone that this propagates rather than edits the template.

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?

Use case is implied: push template changes out to the students who already received the workout. There is no explicit 'use this instead of X' routing to update_workout or list_workout_copies, and no stated preconditions (e.g. template must be published or have copies).

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