garminconnect-js

set_heart_rate_zones

Change a Garmin heart rate zone profile by specifying sport, training method, and zone floors. Since Garmin doesn't recalculate floors automatically, include them in your update.

Instructions

Changes one heart-rate zone profile and returns it as stored. READ-MODIFY-WRITE of one profile: GETs /biometric-service/heartRateZones, overlays {sport? = "DEFAULT", trainingMethod?, maxHeartRate?, restingHeartRate?, lactateThresholdHeartRate?, zoneFloors?: [5 bpm]} with changeState: "CHANGED", PUTs [profile] (204), then returns the profile READ BACK. A sport with no profile starts from DEFAULT's. Setting restingHeartRate also turns off restingHrAutoUpdateUsed. Garmin does NOT recompute floors when the method or a heart rate changes. Send zoneFloors too. Floors must be stric…

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "update": "<update>"
    },
    "name": "set_heart_rate_zones"
  }
}

Input Schema

Name	Required	Description	Default
`update`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 15, 2026

TDQS

A4.5/5.0

Behavior5/5

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

Annotations only give readOnlyHint=false, destructiveHint=false, openWorldHint=true. The description goes well beyond that: it discloses the exact endpoint sequence, the 204 response, the read-back verification, the side effect that setting restingHeartRate disables restingHrAutoUpdateUsed, and the non-obvious domain rule that floors are not recomputed server-side.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loads the one-line purpose, then the mechanics in a compact, information-dense form with no filler. It is long, but nearly every clause carries behavior an agent must know; the truncation is the only real structural flaw.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a mutating tool with a nested object payload, no output schema and no explicit annotation coverage, the description supplies the return behavior ('returns the profile READ BACK'), the side effect, and the server-side non-recomputation caveat. Only the truncated zone-floor validation rule keeps it from being fully self-sufficient.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is nominally low, so the description carries the load: it enumerates the accepted payload fields, pins zoneFloors to '[5 bpm]', and explains the sport-default fallback. It adds real meaning over the bare nested object, though the final constraint sentence is truncated mid-word ('Floors must be stric…'), leaving part of the validation rule unstated.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Changes one heart-rate zone profile') and adds scope ('one profile', not all). The GET/PUT flow makes it clearly distinguishable from the read-only sibling get_heart_rate_zones and from delete_heart_rate_zones without opening any schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives procedural guidance an agent needs: it describes the read-modify-write sequence, notes that a sport without a profile starts from DEFAULT's, and instructs 'Send `zoneFloors` too' with the warning that Garmin does not recompute floors. It never explicitly names when to prefer this over delete_heart_rate_zones or the read tools, so it stops short of full alternative routing.

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

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