MCP error -32602: invalid schema for daily_hrv and daily_body_battery

[MineraleYT]

Description:
Calls to mcp/garmin-connect methods daily_hrv() and daily_body_battery() fail with schema errors.

Error:

MCP error -32602: Structured content does not match the tool's output schema:
data.result should be string,
data.result[0].create_time_stamp/start_timestamp_gmt should match format "date-time"

Repro:

daily_hrv({"end_date":"2025-11-04","days":7})
daily_hrv({})
daily_body_battery({"end_date":"2025-11-04","days":7})

Expected:
Tool output matches MCP schema — timestamps in ISO 8601, and data.result matches expected type.

[coderabbitai]

A summary of the changes CodeRabbit can apply:

• Update src/garth_mcp_server/init.py: add imports (date, datetime, dataclasses), add a recursive _serialize_garth_data() function that converts dataclass objects and nested datetime/date to ISO 8601 strings and serializable dicts (preserving error messages), and wrap the return values of 14 tools (user_profile, user_settings, weekly_intensity_minutes, daily_intensity_minutes, daily_body_battery, daily_hydration, daily_steps, weekly_steps, daily_hrv, hrv_data, daily_sleep, nightly_sleep, daily_stress, weekly_stress) with this serializer to fix MCP JSON schema validation.

• Add BUGFIX_SUMMARY.md and modify src/garth_mcp_server/init.py to fix MCP schema validation by importing datetime and dataclasses, adding a _serialize_garth_data helper (converting dataclass, dict, list, date/datetime to JSON-serializable forms), and wrapping all garth dataclass-returning tool functions (including sleep_data) with this serializer.

• ✅ Create PR with these edits
• 📋 Get copyable edits

[coderabbitai]

🤔 Analyzing the issue and generating a plan...

[MineraleYT]

Any updates? @matin

[matin]

@MineraleYT completely lost track of this. I'll work on it next week

[MineraleYT]

@MineraleYT completely lost track of this. I'll work on it next week

No worries at all. Thank you, actually, for the work you’re doing on this project. I really appreciate it.