garmin_set_hr_zones

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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the mutation/safety profile is covered. The description adds genuinely non-obvious behavior: that max_hr mode recalculates zone floors at 50/60/70/80/90%, plus a user-confirmation requirement. It does not disclose that existing zone floors are replaced or what permissions are needed.

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 short sentences with no waste; the action comes first and the recalculation rule second. The clipped phrasing ('With method max_hr and a new max_hr') is slightly telegraphic but still parseable.

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 six-parameter mutation tool with half the parameters undocumented and no output schema, the description fully covers only the max_hr path. An agent still cannot tell which parameters are required together for hrr, lthr, or custom_bpm, nor whether all five zones are overwritten.

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 only 50%, so the description must compensate, and it partially does by explaining the max_hr pairing and the derived floor percentages. However, resting_hr (for hrr), lactate_threshold_hr (for lthr), and max_hr itself have no documentation in either the schema or the description, leaving the other three methods under-explained.

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: 'Change heart-rate zone settings for a sport', with the sport scope named. It is clearly distinguishable from sibling read tools (garmin_profile, garmin_status) and from other write tools like garmin_set_nutrition_goals, though it never explicitly contrasts with them.

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?

The description gives one operational rule, 'Confirm with the user first', which is useful but is a safety instruction rather than when-to-use guidance. It implies usage via 'With method max_hr and a new max_hr' but never states when to pick max_hr vs hrr/lthr/custom_bpm, nor what prerequisites exist.

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