SPARQL MCP Server

🔭 SPARQL MCP server

A Model Context Protocol (MCP) server to help users write SPARQL queries for open-access SPARQL endpoints, developed for the SIB Expasy portal.

The server will automatically index metadata present in the list of SPARQL endpoints defined in a JSON config file, such as:

SPARQL query examples,
Endpoints schema using the Vocabulary of Interlinked Datasets (VoID), which can be automatically generated using the void-generator.

🧩 Endpoints

The HTTP API comprises 2 main endpoints:

/mcp: MCP server that searches for relevant data to answer a user question using the EOSC Data Commons search API
- Uses rmcp with Streamable HTTP transport
- 🧰 Available tools:
  - access_sparql_resources: retrieve relevant information about the resources to help build a SPARQL query to answer the question (query examples, classes schema)
  - get_resources_info: retrieve relevant information about the SPARQL endpoints resources themselves (e.g. description, list of available endpoints)
  - execute_sparql: execute a SPARQL query against a given endpoint
/chat: optional HTTP POST endpoint (JSON) to query the MCP server via an LLM provider
- Uses axum, utoipa for OpenAPI spec generation, llm to interact with LLM providers (e.g. Mistral, OpenAI)
- Supports streaming response: tool call requested, then tool call results, and final search results.

🚀 Use

Use it through the sparql-mcp package on pip:

uvx sparql-mcp ./sparql-mcp.json

Or download the binary corresponding to your architecture from the releases page.

🛠️ Development

Important

Requirements:

Rust
Protobuf installed (e.g. brew install protobuf)
API key for a LLM provider: Mistral.ai or OpenAI, you can use the free tier, you just need to login

Recommend VSCode extension: rust-analyzer

📥 Install dev dependencies

rustup update
cargo install cargo-release cargo-deny cargo-watch git-cliff

Create a .cargo/config.toml file with your Mistral API key or OpenAI API key:

[env]
MISTRAL_API_KEY = "YOUR_API_KEY"
OPENAI_API_KEY = "YOUR_API_KEY"
GROQ_API_KEY = "YOUR_API_KEY"

⚡️ Start dev server

Start the MCP server in dev at http://localhost:8000/mcp, with OpenAPI UI at http://localhost:8000/docs

cargo run

Customize server configuration through CLI arguments:

cargo run -- --force-index --mcp-only --db-path ./data/lancedb

Provide a custom list of servers through a .json file with:

cargo run -- ./sparql-mcp.json

Example sparql-mcp.json:

{
  "endpoints": [
    {
      "label": "UniProt",
      "endpoint_url": "https://sparql.uniprot.org/sparql/",
      "description": "UniProt is a comprehensive resource for protein sequence and annotation data."
    },
    {
      "label": "Bgee",
      "endpoint_url": "https://www.bgee.org/sparql/",
      "description": "Bgee is a database for retrieval and comparison of gene expression patterns across multiple animal species.",
      "homepage_url": "https://www.bgee.org/"
    }
  ]
}

Tip

Run and reload on change to the code:

cargo watch -x run

Note

Example curl request:

curl -X POST http://localhost:8000/search -H "Content-Type: application/json" -H "Authorization: SECRET_KEY" -d '{"messages": [{"role": "user", "content": "What is the HGNC symbol for the P68871 protein?"}], "model": "mistral/mistral-small-latest", "stream": true}'

Recommended model per supported provider:

openai/gpt-4.1
mistralai/mistral-large-latest
groq/moonshotai/kimi-k2-instruct

🔌 Connect MCP client

Follow the instructions of your client, and use the /mcp URL of your deployed server (e.g. http://localhost:8000/mcp)

🐙 VSCode GitHub Copilot

Add a new MCP server through the VSCode UI:

Open the Command Palette (ctrl+shift+p or cmd+shift+p)
Search for MCP: Add Server...
Choose HTTP, and provide the MCP server URL http://localhost:8000/mcp

Your VSCode mcp.json should look like:

{
    "servers": {
        "sparql-mcp-server": {
            "url": "http://localhost:8000/mcp",
            "type": "http"
        }
    },
    "inputs": []
}

📦 Build for production

Build binary in target/release/

cargo build --release

Note

Start the server with (change flags at your convenience):

./target/release/sparql-mcp ./sparql-mcp.json --force-index

Start using the python wheel:

uvx --from ./target/release/sparql_mcp-0.1.0-py3-none-any.whl . sparql-mcp

🐍 Build python package

Require uv installed

Bundle the CLI as python package in target/wheels:

uvx maturin build

🐳 Deploy with Docker

Create a keys.env file with the API keys:

MISTRAL_API_KEY=YOUR_API_KEY
SEARCH_API_KEY=SECRET_KEY_YOU_CAN_USE_IN_FRONTEND_TO_AVOID_SPAM

Tip

SEARCH_API_KEY can be used to add a layer of protection against bots that might spam the LLM, if not provided no API key will be needed to query the API.

Build and deploy the service:

docker compose up

🧼 Format & lint

Automatically format the codebase using rustfmt:

cargo fmt

Lint with clippy:

cargo clippy --all

Automatically apply possible fixes:

cargo fix

⛓️ Check supply chain

Check the dependency supply chain: licenses (only accept dependencies with OSI or FSF approved licenses), and vulnerabilities (CVE advisories).

cargo deny check

Update dependencies in Cargo.lock:

cargo update

🏷️ Release

Dry run:

cargo release patch

Or minor / major

Create release:

cargo release patch --execute

SPARQL MCP Server