MCP + Gemini (Project Demo)

A tiny, ready-to-run MCP server (SQLite) you can use to test Gemini CLI’s MCP integration at project scope.

What it does

• Spins up a minimal MCP server (stdio) exposing:

  • Tool: run_sql(sql, limit=50) — read-only SELECT queries
  • (Optional) Resource: schema://sqlite (see schema)

• Uses a local SQLite DB: demo.db

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Requirements

• Python 3.9+
• uv installed (pipx install uv or package manager)
• Gemini CLI installed and logged in (gemini --help works)

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Project structure

.
├── server.py        # FastMCP server (stdio)
├── demo.db          # sample SQLite DB (auto-created/seeded)
├── pyproject.toml   # managed by uv
└── uv.lock

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Setup (with uv)

# clone your repo, then:
uv sync

# (optional) pin DB location (defaults to demo.db)
export MCP_SQLITE_PATH=demo.db

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Run locally (MCP Inspector - optional)

uv run mcp dev server.py
# opens the Inspector UI; try:
# - Resource: schema://sqlite
# - Tool: run_sql  {"sql":"SELECT * FROM users","limit":5}

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Add to Gemini CLI at project level

Run these from the project root (so it’s saved to .gemini/settings.json).

# add the MCP server (stdio) to THIS project
gemini mcp add sqlite-demo uv run server.py -s project \
  --description "MCP server to query a local SQLite DB (read-only)."

# verify
gemini mcp list -s project
# (shows: ✓ sqlite-demo: uv run server.py (stdio) - Connected)

Use it in a Gemini chat

gemini
# then in the prompt:
# > Get number of users

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Typical commands you’ll run

# run the server standalone (stdio mode)
uv run server.py

# seed/reset demo DB (server creates + seeds on first run)
rm -f demo.db && uv run server.py  # then Ctrl+C

# change DB file
export MCP_SQLITE_PATH=/path/to/your.db

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Example queries (inside Gemini)

• “List tables in the DB using sqlite-demo.”
• “Get number of users”

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Troubleshooting

• No logs on start (stdio): stdout is used by JSON-RPC. Use logging (stderr) or the Inspector’s debug view.

• Gemini doesn’t see the server: ensure you added with -s project from this folder; check .gemini/settings.json.

• uv not found: use full path or swap to python:

  # If you ever add Codex later, project-local .codex/config.toml would look like:
  [mcp_servers.sqlite-demo]
  command = "python"
  args = ["server.py"]
  env = { MCP_SQLITE_PATH = "demo.db" }
  

• Port expectations: this demo uses stdio (no port). If you need HTTP:

  # server.py (switch transport)
  if __name__ == "__main__":
      mcp.run(transport="streamable-http")
  

  Then register with Gemini using -t http and a URL (requires mounting into an HTTP app).

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Notes

• The tool only allows SELECT (safe read-only).
• Rename tools and server for multi-DB setups (e.g., Users DB, Orders DB) and give each a clear --description.

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License

This project is licensed under the MIT License – see the LICENSE file for details.