google-health-worker-mcp

Personal remote MCP server on Cloudflare Workers that connects Claude (iPhone / desktop / web via Custom Connector) to Google Health API v4 — read activity, sleep, heart rate, SpO₂, HRV, respiratory rate, skin temperature, weight and nutrition.

All 16 HealthProvider read methods run on Google Health v4 (GoogleHealthProvider). This edition exposes the read surface; the write/delete methods are present in the interface but not implemented.

Based on tachibanayu24/fitbit-googlehealth-mcp (MIT). Upstream docs preserved under docs/upstream-*.

Why

The legacy Fitbit Web API shuts down in September 2026. Google Health API v4 is its successor. This project keeps the upstream's Workers / Hono / MCP architecture — the only form factor usable from the Claude mobile app — and swaps the data source to v4.

Related MCP server: Garmin Connect MCP Server

Capabilities

The HealthProvider interface also declares write/delete methods (logFood, logWeight, …); in this edition they throw "not implemented".

Skin temperature is confirmed absolute °C + baseline; the mapper reports the nightly-relative delta. Reconcile calls omit filter (v4 filter members are type-specific and mostly 400); range narrowing is done client-side on the civil date.

Setup

One-time bootstrap.

Google Cloud (console):

1. Create a project → APIs & Services → enable Health API.

2. OAuth consent screen (User type External): add the read scopes below, add your own Gmail as a test user, then Publish the app to "In production". (Testing-mode refresh tokens expire after 7 days, which breaks an unattended Worker.)

3. Credentials → create an OAuth client (Web application), Authorized redirect URI http://127.0.0.1:8787/oauth/callback. Note the client id / secret.

Read scopes (prefix https://www.googleapis.com/auth/):

googlehealth.profile.readonly
googlehealth.settings.readonly
googlehealth.activity_and_fitness.readonly
googlehealth.health_metrics_and_measurements.readonly
googlehealth.sleep.readonly
googlehealth.nutrition.readonly

Do not add include_granted_scopes to the authorization URL — mixing legacy scopes can cause 403s on reads. Use access_type=offline&prompt=consent to get a refresh token.

This repo:

pnpm install                      # you run this — deps are never auto-installed

cp wrangler.toml.example wrangler.toml
pnpm wrangler kv namespace create TOKENS   # paste ids into wrangler.toml
pnpm wrangler kv namespace create CACHE

export GOOGLE_CLIENT_ID=...        # the Web OAuth client from above
export GOOGLE_CLIENT_SECRET=...
pnpm run setup:google             # browser consent -> prints wrangler secret/kv commands

pnpm deploy                       # then add the Custom Connector in claude.ai:
                                  #   https://<worker>.workers.dev/mcp/<MCP_SHARED_SECRET>

MCP_SHARED_SECRET must be hex (openssl rand -hex 32) — it is embedded in the URL path, so base64's / would break routing. Secrets live in Cloudflare, tokens in KV — never in this repo.

Architecture

Claude (mobile / desktop / web)
  │ Streamable HTTP  /mcp/<SECRET>
  ▼
Cloudflare Workers
  ├─ guard (shared secret + Anthropic CIDR allowlist)
  ├─ @hono/mcp (Streamable HTTP transport)
  └─ McpServer → tools/* → HealthProvider
                              └─ GoogleHealthProvider → health.googleapis.com/v4
  KV: TOKENS (Google OAuth refresh/access) · CACHE (read cache)

Two auth layers: ① Claude → Worker = shared secret in the URL path + Anthropic CIDR allowlist; ② Worker → Google = KV refresh token, auto-refreshed. The tools layer is provider-agnostic (HealthProvider); swapping Fitbit → Google was one line in src/server.ts.

Development

pnpm typecheck     # tsc --noEmit
pnpm test          # vitest (113 tests)
pnpm lint          # biome
pnpm deploy        # wrangler deploy

Provider field mappings are covered by fixture tests using shapes probed from the live v4 API. Deployment: connect the repo in Cloudflare Workers Builds (dashboard → Workers → Builds → connect GitHub) so push main runs install + test + wrangler deploy automatically.

Documents

License

MIT — see LICENSE (upstream copyright preserved).