Fitbit MCP Server

get_heart_rate

Obtain heart rate data for a specified time period (1d, 7d, 30d, etc.) ending today or on a given date.

Instructions

Get the raw JSON response for heart rate data from Fitbit for a specified period ending today or on a specific date. Requires a 'period' parameter such as '1d', '7d', '30d', '1w', '1m' and optionally accepts 'date' parameter.

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": {
      "period": "<period>"
    },
    "name": "get_heart_rate"
  }
}

Input Schema

Name	Required	Description	Default
`period`	Yes	The time period for which to retrieve heart rate data.
`date`	No	The date for which to retrieve heart rate data (YYYY-MM-DD or 'today'). Defaults to 'today'.

Schema Changelog

Changes observed during successful MCP inspections.

Addedv1.0.0Jan 3, 2026

TDQS

A3.5/5.0

Behavior2/5

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

With no annotations, the description should fully disclose behavioral traits. It mentions returning 'raw JSON response' but omits critical details such as authentication requirements, rate limits, error handling, or what happens if data is unavailable. This leaves significant gaps for an agent to infer.

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

Conciseness5/5

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

The description is two sentences long, directly to the point, and includes all essential information without any extraneous content.

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

Completeness3/5

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

Given the lack of output schema and annotations, the description provides basic parameter usage but fails to clarify the structure of the 'raw JSON response' or error scenarios. It is minimally adequate for a simple tool but leaves room for ambiguity.

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

Parameters3/5

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

Schema coverage is 100% and the description merely repeats the enum values for 'period' and the format for 'date', adding no new semantic meaning beyond what the schema already provides.

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?

The description clearly states the verb 'Get', the resource 'raw JSON response for heart rate data from Fitbit', and specifies the scope 'for a specified period ending today or on a specific date'. It distinguishes from the sibling 'get_heart_rate_by_date_range' by focusing on period-based retrieval.

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

Usage Guidelines3/5

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

The description explains that a 'period' parameter is required and an optional 'date' can be used, which implies usage context. However, it does not provide explicit guidance on when to use this tool over the sibling 'get_heart_rate_by_date_range' or any exclusion criteria.

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

Deploy Server