Weather Prediction MCP Server + Agent

Homework submission for 2026-08-08: a FastMCP weather server, a grounded Databricks Agent Bricks configuration, and an optional weather dashboard. The project follows the architectural pattern of Day 3's paper-trading project but uses original weather-domain code and Open-Meteo instead of copying the trading implementation.

Open-Meteo was selected because its public non-commercial API needs no signup, API key, paid tier, or Databricks secret. Place and postal-code lookup uses Open-Meteo's GeoNames-backed geocoding endpoint.

Architecture

Natural-language question
          |
          v
Databricks Agent Bricks
  (agent/system_prompt.md)
          |
          | streamable HTTP tool call
          v
MCP Databricks App                    Optional dashboard Databricks App
mcp_server/weather_mcp_server.py      dashboard/app.py
          |                                      |
          +---------- weather adapter -----------+
                              |
                              | HTTPS + normalized dicts
                              v
                    Open-Meteo Forecast + Geocoding APIs

mcp_server/ and dashboard/ are independently deployable Databricks Apps. Each contains its own adapter copy because an App is deployed from one source subfolder. A contract test prevents those copies from drifting.

Related MCP server: mcp-open-meteo

MCP tools

The recommendation is deliberately transparent: umbrella at at least 40% precipitation probability or 1 mm precipitation, jacket below an 18°C high or 10°C low, heat precautions at a 30°C high, and wind caution at 40 km/h. It returns both the decision and the values/rules that caused it.

All HTTP, retry, location resolution, response parsing, and decision logic is in weather_adapter.py. Decorated functions only call the adapter and translate errors into safe {"status": "error", ...} results. No stack trace, secret, or raw upstream exception is returned to the agent.

Repository layout

mcp_server/
  weather_mcp_server.py    FastMCP tools and streamable-HTTP entry point
  weather_adapter.py       Open-Meteo HTTP adapter and recommendation logic
  app.yaml                 MCP Databricks App command
  requirements.txt
dashboard/
  app.py                   Optional Streamlit dashboard
  weather_adapter.py       Independent App copy of the adapter
  app.yaml
  requirements.txt
agent/
  system_prompt.md         Agent Bricks instructions and guardrails
  external_mcp.json        Endpoint/tool registration checklist
  demo_questions.md        Three required demonstration scenarios
docs/evidence/             Safe place for redacted deployment screenshots
tests/                     Unit and project-contract tests (no live API required)

Local development

Use Python 3.10 or later:

python -m venv .venv
source .venv/bin/activate
pip install -r requirements-dev.txt
pytest -q

Run the MCP server:

cd mcp_server
python weather_mcp_server.py

It listens on http://localhost:8000; the streamable-HTTP endpoint is http://localhost:8000/mcp. Use MCP Inspector or another MCP client to list and call tools. In another terminal, run the optional dashboard:

cd dashboard
pip install -r requirements.txt
streamlit run app.py

No .env or credential is required. The tests use fake HTTP sessions and are repeatable without network access.

Deploy the MCP server App

The commands below use the current Databricks Apps flow. You can perform the same steps in Compute > Apps and point the App at the mcp_server/ source folder.

databricks auth login --host https://<workspace-hostname>
databricks apps create mcp-weather-prediction

DATABRICKS_USERNAME=$(databricks current-user me | jq -r .userName)
databricks sync mcp_server "/Users/$DATABRICKS_USERNAME/mcp-weather-prediction"
databricks apps deploy mcp-weather-prediction \
  --source-code-path "/Workspace/Users/$DATABRICKS_USERNAME/mcp-weather-prediction"

Wait for the App to reach Running, copy its URL, and use https://<app-url>/mcp as the MCP endpoint. Access is controlled by the Databricks App's permissions. No weather secret or resource binding is needed.

Official references:

• Host your own MCP server as a Databricks App

• Use MCP servers in agents

• Open-Meteo forecast API

• Open-Meteo geocoding API

Register and build the Agent Bricks agent

Workspace UI labels can vary by preview version. Following the Day 3 workflow:

1. Open AI Gateway > MCPs and add/register a custom MCP server.

2. Enter weather-prediction as its name and the deployed https://<app-url>/mcp endpoint. If the UI asks for the backing Databricks App instead, select mcp-weather-prediction.

3. Confirm that all four tools in agent/external_mcp.json are discovered and grant the agent/user permission to invoke the App or governed MCP service.

4. Open Agents > Agent Bricks > Create agent, choose the available custom tool-calling agent type, and add the registered MCP server under Tools.

5. Paste the full contents of agent/system_prompt.md into the system prompt. The prompt requires weather tool calls, defines tool order, handles ambiguous locations and errors, and forbids guessed weather.

6. Evaluate with the three prompts in agent/demo_questions.md, then deploy the agent only after its tool traces and answers are grounded.

Do not replace the evidence placeholders with invented output. Capture actual Agent Bricks tool calls/final answers after workspace deployment and add redacted screenshots under docs/evidence/ or paste transcripts into the demo file.

Deploy the optional dashboard App

databricks apps create weather-planner-dashboard
databricks sync dashboard "/Users/$DATABRICKS_USERNAME/weather-planner-dashboard"
databricks apps deploy weather-planner-dashboard \
  --source-code-path "/Workspace/Users/$DATABRICKS_USERNAME/weather-planner-dashboard"

The dashboard shows current conditions, a multi-day forecast, one transparent planning recommendation, and the last ten checks in the current browser session. It does not claim to persist or display Agent Bricks traces.

Error handling and limitations

• Ambiguous or missing places return a location error and invite clarification.

• Coordinates are range-checked; forecast days are limited to Open-Meteo's 16-day window; recommendation dates must be present in the returned forecast.

• HTTP requests use timeouts and retry rate limits/transient 5xx responses.

• Forecasts are predictions, not guarantees. This project does not expose severe-weather alerts; users should consult their official local authority for safety decisions.

• A place-name lookup selects Open-Meteo's first geocoding result. Include a region/country or coordinates when a name is ambiguous.

• The optional dashboard history is browser-session state, not durable storage.

Submission checklist

• FastMCP server with streamable HTTP

• Separate HTTP/parsing adapter

• Current conditions tool

• 1–16 day forecast tool

• Derived recommendation with documented thresholds

• Stretch city-comparison tool

• Clean errors and no committed API keys

• requirements.txt and app.yaml for both Apps

• Agent tool list and specific system prompt

• Three demonstration prompts prepared

• MCP App URL added after deployment

• Agent Bricks tool-call/final-answer evidence added after deployment

• Optional dashboard URL/screenshot added after deployment

Reference pattern

Architecture and deployment flow were informed by databricks-lakebase-app-day-3 and the local weather-intelligence / dbbc-helpdesk repositories. This repo is an original implementation: the trading broker was replaced with a focused Open-Meteo adapter, the MCP surface is weather-specific, and the tests and guardrails are written for weather planning.