create_library_workout

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

Annotations only cover hints (readOnlyHint=false, destructiveHint=false, openWorldHint=false); the description adds real behavior: workout_doc is validated and nothing is created on error, an empty workout_doc is ignored in favor of description, and dry_run returns the exact request without writing. It also discloses the post-write readback ('the answer reads back what Intervals.icu stored and parsed'), which is non-obvious for a mutation.

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 gating condition, then write semantics, then the dry_run behavior and the scheduling hand-off. Every sentence contributes, though the third sentence packs several distinct rules (validation, empty-doc fallback, format reference) densely enough that it reads as a run-on.

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 9-parameter mutation with no output schema, the description covers failure semantics, dry-run preview, precedence, and return readback, and defers deep syntax to a named guide. Missing only operational detail such as duplicate-name handling or required permissions in Intervals.icu.

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 100%, so the baseline is 3, and the description goes beyond it by clarifying the precedence rule between workout_doc and description and by defining what dry_run returns, not just what it is. It does not restate the schema, but nor does it add syntax detail for nested Step/Value fields beyond pointing at intervals://workout-syntax.

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?

Specific verb+resource ('save a workout template in the workout library') with an explicit scope qualifier ('Use only when...'). It is clearly distinguished from get_library_workout (read) and add_event_from_library (scheduling), so an agent can select it without opening a schema.

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?

States the triggering condition ('only when the athlete asks to save a workout template') and routes the adjacent use case elsewhere ('Schedule it with add_event_from_library'). It also points to get_guide for the workout-syntax reference, which is the correct escalation path.

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