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

Annotations already declare it is a mutating but non-destructive, non-open-world operation, so the description only needs to add context — and it does, with the ordering constraint "Workout cannot start or end with rest," a validation rule an agent would otherwise discover via a failed call. It omits permission/scope behavior around team_id and default visibility, which keeps it from a 5.

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?

Four tight sentences with no filler: purpose, trigger, input choice, and constraint, in that priority order. The most consequential rule (can't start/end with rest) is placed last where it stands out as an exception rather than buried.

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?

An output schema exists, so return values need not be explained, and the core input decision plus the rest-position constraint are covered. But for an 8-parameter creation tool with 0% schema description coverage, the absence of any guidance on team_id or visibility defaults leaves real gaps.

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 0%, so the description must carry parameter meaning, and it does resolve the most important ambiguity by explaining the exercise_map vs instances alternative and the provenance of instance IDs. However, six of eight parameters (team_id, difficulty, visibility, description, category_ids, name) get no mention at all, leaving the description partial against a 0% coverage schema.

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 ("Creates a workout") and names the building blocks it consumes (exercise and rest instances). It implicitly separates itself from generate_workout by framing this as the path for a "custom workout," but it never names the generation sibling explicitly, so the differentiation is inferential rather than stated.

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 when the user wants to build a custom workout" gives a clear triggering condition, and it further says to supply either exercise_map or instances, mirroring the anyOf. It stops short of naming an alternative tool (e.g. generate_workout) that an agent should pick instead when it does not have pre-built instances.

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