update_menstrual_settings

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

Annotations already cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true), so the bar is lower, and the description still adds meaningful behavior: it discloses the exact multi-step GET-overlay-PUT flow, the validation failure (empty `settings` throws `GarminError`), and that the update is a merge rather than a replace. What it omits is the full set of POST/PUT side effects or what a partial overlay does to unmentioned fields.

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?

It is a single dense sentence, but it is front-loaded with the critical validation constraint and every clause (validation, GET, overlay, PUT, id resolution) carries operational value. The run-on semicolon structure is slightly heavy but wastes nothing.

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 nested-object mutation with no output schema and 0% schema coverage, the description supplies the mechanics an agent needs to call it correctly (merge behavior, required non-empty settings, endpoint flow, id handling). It leaves gaps on the allowable contents of `settings` and error cases beyond the empty check, but is otherwise complete.

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 0% schema coverage the description must carry parameter meaning, and it does: it explains that `settings` is overlaid onto existing userMenstrualCycleSettings (patch semantics for the free-form object), that it must be non-empty, and that options.userSettingsId feeds the `id` when resolvable. It adds real semantics beyond the bare schema, though the valid keys inside `settings` remain undocumented.

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 name says 'update_menstrual_settings' and the description reveals the operation overlays `settings` onto the current `userMenstrualCycleSettings`, so the resource and mutation are inferable. However, it never states a plain purpose sentence and does nothing to distinguish this from close siblings like update_menstrual_calendar, update_menstrual_daily_log, or init_menstrual_cycle_setup — it jumps straight into implementation mechanics.

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?

There is no guidance on when to use this tool versus the several other menstrual-related mutators in the sibling list. No prerequisites, no exclusions, and no alternative routing are mentioned; the only condition given (non-empty `settings`) is a runtime validation rule, not usage guidance.

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