VAMDC MCP Server

A Model Context Protocol (MCP) server for accessing VAMDC (Virtual Atomic and Molecular Data Centre) spectroscopic databases.

Overview

MCP server providing access to VAMDC spectroscopic databases through the Model Context Protocol. Built on pyVAMDC for querying atomic and molecular data from distributed databases worldwide.

Features

• 5 MCP Tools for querying spectroscopic data:

  • get_server_info - Server capabilities and metadata
  • get_nodes - List all available VAMDC database nodes (33 databases)
  • get_species - Get chemical species data (4,952+ species)
  • get_species_by_node - Filter species by specific database node
  • get_lines - Query spectral lines within wavelength range

• Dual Transport Support:

  • HTTP (Streamable HTTP) - For web/remote access
  • stdio - For desktop MCP clients (Claude Desktop, IDEs)

• Clean Architecture: Module-level tool registration, async execution with thread pools

Requirements

• Python 3.13+
• uv package manager

Installation

Clone the repository:

git clone https://github.com/VAMDC/vamdc-mcp.git
cd vamdc-mcp

No additional installation needed - uv will handle dependencies automatically.

Usage

Starting the Server

HTTP Transport (Default)

Start the server with HTTP transport for web/remote access:

uv run server.py --transport http --port 8888

The server will be available at http://localhost:8888/mcp

Change port (optional):

uv run server.py --transport http --port 9000

stdio Transport

Start the server with stdio transport for desktop MCP clients:

uv run server.py --transport stdio

This mode is used by desktop applications like Claude Desktop, VSCode extensions, etc.

Command Line Options

uv run server.py --help

Options:

• --transport {http,stdio} - Transport protocol (default: http)
• --port PORT - Port for HTTP transport (default: 8888)

Examples

HTTP Transport Example

Using curl to interact with the HTTP server:

# 1. Initialize the session
curl -X POST "http://localhost:8888/mcp" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{
    "jsonrpc":"2.0",
    "id":1,
    "method":"initialize",
    "params":{
      "protocolVersion":"2025-03-26",
      "capabilities":{},
      "clientInfo":{"name":"test-client","version":"1.0.0"}
    }
  }'

# 2. List available tools
curl -X POST "http://localhost:8888/mcp" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/list"}'

# 3. Get database nodes
curl -X POST "http://localhost:8888/mcp" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{
    "jsonrpc":"2.0",
    "id":3,
    "method":"tools/call",
    "params":{"name":"get_nodes","arguments":{}}
  }'

# 4. Get species from specific node (AMDIS Ionization)
curl -X POST "http://localhost:8888/mcp" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{
    "jsonrpc":"2.0",
    "id":4,
    "method":"tools/call",
    "params":{
      "name":"get_species_by_node",
      "arguments":{"node_url":"http://dbshino.nifs.ac.jp:4000/vamdc/tap/"}
    }
  }'

# 5. Query spectral lines (1000-1500 Angstrom, Magnesium from VALD)
curl -X POST "http://localhost:8888/mcp" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{
    "jsonrpc":"2.0",
    "id":5,
    "method":"tools/call",
    "params":{
      "name":"get_lines",
      "arguments":{
        "lambda_min":1000.0,
        "lambda_max":1500.0,
        "listNodes":["http://vald.astro.uu.se/atoms-12.07/tap/"],
        "listSpecies":["FYYHWMGAXLPEAU-UHFFFAOYSA-N"]
      }
    }
  }'

stdio Transport Example

Using echo/pipe for stdio communication:

# Send initialize request
echo '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}' | uv run server.py --transport stdio

# Interactive session with multiple requests
cat <<'EOF' | uv run server.py --transport stdio
{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}
{"jsonrpc":"2.0","method":"notifications/initialized"}
{"jsonrpc":"2.0","id":2,"method":"tools/list"}
{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"get_server_info","arguments":{}}}
EOF

Claude Desktop Configuration

To use with Claude Desktop, add to your Claude Desktop config file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json Windows: %APPDATA%\Claude\claude_desktop_config.json

Option 1: Using the start script (recommended)

{
  "mcpServers": {
    "vamdc": {
      "command": "bash",
      "args": ["/path/to/vamdc-mcp/start_server.sh"]
    }
  }
}

Option 2: Direct uv command

{
  "mcpServers": {
    "vamdc": {
      "command": "uv",
      "args": [
        "run",
        "--directory",
        "/path/to/vamdc-mcp",
        "server.py",
        "--transport",
        "stdio"
      ]
    }
  }
}

Replace /path/to/vamdc-mcp with the actual path to your cloned repository.

Note: The start_server.sh script is included for convenience and handles directory navigation automatically.

OpenAI Codex

Adding the local MCP to Codex just takes this command, run from within the base directory of this repository:

codex mcp add vamdc -- uv run server.py --transport stdio

After that, the tools are available in Codex sessions.

Available Tools

1. get_server_info

Get server metadata and capabilities.

Parameters: None

Returns: Server name, version, available tools list

2. get_nodes

List all VAMDC database nodes.

Parameters: None

Returns: 33 database nodes with metadata (name, TAP endpoint, topics, contact info)

3. get_species

Get all chemical species data.

Parameters:

• state (string): State filter (currently not implemented, accepts any value)

Returns: 4,952+ species with InChI, InChIKey, formulas, charges, masses

4. get_species_by_node

Filter species by specific database node.

Parameters:

• node_url (string): TAP endpoint URL of the database node
  • Example: "http://vald.astro.uu.se/atoms-12.07/tap/"

Returns: Filtered species list from specified node

5. get_lines

Query spectral lines within wavelength range.

Parameters:

• lambda_min (float): Lower wavelength bound in Angstrom (required)
• lambda_max (float): Upper wavelength bound in Angstrom (required)
• listNodes (array of strings, optional): Filter by TAP endpoint URLs
• listSpecies (array of strings, optional): Filter by InChIKeys

Returns: Spectral line data including frequencies, Einstein coefficients, energy levels, quantum numbers

Note: This tool queries remote VAMDC databases, which may be slow or timeout depending on the wavelength range and filters.

Architecture

• FastMCP Framework: Built on the official MCP Python implementation
• Async Execution: Thread pool execution for blocking database operations
• Stateless HTTP: No session state maintained between requests
• Module-level Tools: Clean, flat structure for easy maintenance

Dependencies

Managed automatically by uv:

• mcp - Model Context Protocol implementation
• uvicorn - ASGI server for HTTP transport
• pyVAMDC - Python interface to VAMDC databases (GitHub)
  • Handles queries to remote VAMDC TAP endpoints
  • Processes spectroscopic data from multiple databases
  • Provides filtering and data manipulation utilities

Testing

See mcp_server_test_log.md for comprehensive testing documentation.

Protocol Version

Implements MCP protocol version 2025-03-26

License

See repository for license information.

Contributing

Contributions welcome! Please open an issue or pull request on GitHub.

Links

• VAMDC Portal
• Model Context Protocol
• GitHub Repository