lsfusion/mcp

lsfusion-mcp

An extensible MCP server hosting multiple tools for lsFusion development. Ships with RAG search tools, syntax validation, and mandatory guidance.

Transports:

• STDIO for local development / desktop MCP clients.
• Streamable HTTP for production via Uvicorn (mounted at /mcp).

Core Tools

• lsfusion_get_guidance(): Fetch mandatory brief and rules.
• lsfusion_retrieve_docs(query: string): Official documentation search.
• lsfusion_retrieve_howtos(query: string): How-tos and combined scenarios.
• lsfusion_retrieve_community(query: string): Tutorials and community discussions.
• lsfusion_validate_syntax(text: string): Syntax validation for lsFusion statements.

Quickstart (local)

python -m venv .venv && source .venv/bin/activate
pip install -r requirements.txt

export OPENAI_API_KEY=sk-...        PINECONE_API_KEY=...        PINECONE_INDEX=lsfusion        PINECONE_NAMESPACE=""

# STDIO transport
python server.py stdio

# HTTP transport
python server.py http --host 0.0.0.0 --port 8000

Claude Desktop / MCP Inspector (STDIO)

mcp install server.py
mcp dev server.py

Adding new tools

Create a new module under tools/ and register it with @mcp.tool() in server.py (or build an auto-discovery if you prefer). Keep tool signatures simple and JSON-serializable.

Contract / output for lsfusion_retrieve_*

Returns an array of objects:

{
  "docs": [
    { "source": "documentation-how-to", "text": "....", "score": 0.73 },
    { "source": "articles", "text": "....", "score": 0.69 }
  ]
}

Sorted by score descending. Structured output is enabled.

Environment variables

• OPENAI_API_KEY — OpenAI API key
• PINECONE_API_KEY — Pinecone API key
• PINECONE_INDEX — Pinecone index name (default lsfusion)
• PINECONE_NAMESPACE — Pinecone namespace (default empty)
• EMBEDDING_MODEL — OpenAI embedding model (default text-embedding-3-large)

Docker

Build and run:

docker build -t lsfusion/mcp:latest .
docker run --rm -p 8000:8000 \
  -e OPENAI_API_KEY=$OPENAI_API_KEY \
  -e PINECONE_API_KEY=$PINECONE_API_KEY \
  lsfusion/mcp:latest

Or via Compose:

docker compose up --build

Production secrets (where to store keys)

Do not hardcode secrets. Options:

1. Kubernetes Secrets + external secret store

   • Store secrets in AWS Secrets Manager / GCP Secret Manager / HashiCorp Vault.
   • Sync into K8s as Secret via External Secrets Operator.
   • Mount as env vars in the Deployment:

     env:
       - name: OPENAI_API_KEY
         valueFrom: { secretKeyRef: { name: mcp-secrets, key: openai } }
       - name: PINECONE_API_KEY
         valueFrom: { secretKeyRef: { name: mcp-secrets, key: pinecone } }
     

2. Docker Swarm / Compose secrets

   • Use secrets: and mount files into the container, then export into env at entrypoint:

     services:
       mcp:
         image: lsfusion/mcp:latest
         secrets: [openai_key, pinecone_key]
     secrets:
       openai_key: { file: ./secrets/openai_key.txt }
       pinecone_key: { file: ./secrets/pinecone_key.txt }
     

   • Read them in an entrypoint script:

     export OPENAI_API_KEY="$(cat /run/secrets/openai_key)"
     export PINECONE_API_KEY="$(cat /run/secrets/pinecone_key)"
     exec python server.py http --host 0.0.0.0 --port 8000
     

3. Cloud run / App services (ECS, Cloud Run, App Service)

   • Inject as environment variables wired to a managed secret store (e.g., AWS Parameter Store / Secrets Manager).
   • Rotate periodically; grant least-privilege IAM.

4. CI/CD (GitHub Actions)

   • Store in Actions Secrets.
   • At build/deploy time pass them into the container as env vars or bake only into the runtime environment (never into the image).

This app reads credentials from environment variables, so your orchestrator should inject them from a secure store. Prefer secret stores over committing .env files.

Hardening checklist

• Run as non-root (done in Dockerfile).
• Keep logs to stdout/stderr; in STDIO mode, avoid extra prints (MCP uses stdio).
• Set request timeouts and retries in your MCP client / reverse proxy.
• Add health endpoint (optional) and readiness checks on /mcp handshake.

HTTP transport configuration (FastMCP)

FastMCP reads host/port from environment variables:

• MCP_HOST (default: 127.0.0.1)
• MCP_PORT (default: 8000)

Examples:

Local run

export OPENAI_API_KEY=sk-... PINECONE_API_KEY=...
export MCP_HOST=0.0.0.0 MCP_PORT=8000
python server.py http

Docker

docker run --rm -p 8000:8000 \  -e OPENAI_API_KEY=$OPENAI_API_KEY \  -e PINECONE_API_KEY=$PINECONE_API_KEY \  -e MCP_HOST=0.0.0.0 \  -e MCP_PORT=8000 \  ghcr.io/<org>/<repo>/lsfusion-mcp:latest