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

The annotations already declare a non-read-only, non-destructive, closed-world mutation. The description adds meaningful behavioral context beyond that: rest instance IDs must be wired into create_workout's exercise_map, and rest cannot be at the start or end of a workout. It does not discuss permissions, team scoping, or whether instances are reusable, but the key placement constraint is disclosed.

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 two tight sentences with no wasted words. The purpose is front-loaded, and the workflow constraint follows immediately.

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 simple two-parameter creation tool with annotations and an output schema, the description covers the central workflow and the start/end constraint well. However, it leaves team_id's role and optionality ambiguous, which matters for correctly invoking a team-scoped create operation.

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 0%, so the description must compensate. It does not explain what team_id means or when it should be supplied, nor does it clarify the duration_seconds minimum of 1 beyond the property name itself.

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: 'Creates a rest/break instance for use between exercises in a workout.' It clearly distinguishes this from the sibling create_exercise_instance tool by emphasizing rest/break usage between exercises.

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 explicitly says to use this when building a workout manually, describes the sequence of creating rest instances and including their IDs in create_workout exercise_map, and names the create_workout sibling. It also states the important restriction that a workout cannot start or end with rest.

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