datomic

🚀 Datomic MCP Server

Installation

Run this command in your terminal to add the MCP server to Claude Code.

Run in terminal:

Command

claude mcp add --transport stdio xlisp-datomic-mcp-server npx -y xlisp-datomic-mcp-server \
  --env JAVA_HOME="path/to/java/home (optional: required if running Datomic client locally)" \
  --env DATOMIC_URL="datomic:core:dev-local://localhost:4334/datomic-demo (adjust to your Datomic URL)"

How to use

This MCP server is built to connect to Datomic databases and expose AI-friendly tooling through JSON-RPC. It enables querying entity relationships, performing aggregate analyses, and exploring entity history with as-of, since, and transaction-time navigation. You can launch the server from a Clojure CLI environment or integrate it into an AI workflow by piping JSON-RPC payloads to STDIO. Once running, you can use the provided tools to query Datomic data, fetch attributes, and reason about relationships in familiar AI pipelines.

How to install

Prerequisites:

Java (JDK 8+ recommended for certain Datomic components, or as required by your Datomic setup)
Clojure CLI installed (clj, clojure) if you plan to run the MCP server directly from source
Datomic database accessible (SQL, Dev-local, or Cloud) with appropriate credentials

Installation steps:

Ensure Java is installed and JAVA_HOME is set if required by your environment.
Install Clojure CLI: follow https://clojure.org/guides/install_clojure
Install/prepare the MCP server package (if using an npm-based wrapper in this workflow, or ensure the repository is available locally):
- If using npm: npm install -g xlisp-datomic-mcp-server (depends on packaging)
Start the MCP server using the recommended command from the README (example shown):
- clojure -X:mcp
- or (mcp-server) from an Emacs REPL as shown in the README
Verify health by sending a JSON-RPC initialize message to STDIO or the configured transport, as described in the README.

Additional notes

Tips and common issues:

Ensure your Datomic URL is reachable from the MCP server host. Network/VPN restrictions can block connections to Datomic Cloud or SQL endpoints.
For Datomic transactor setups, ensure the correct Java version is used to avoid ActiveMQ-related errors.
When using STDIO transport, make sure your tooling can consume and emit JSON-RPC 2.0 messages as shown in the health check example.
If running via npx or npm wrappers, verify the package name and registry availability; local development may require adjusting the package reference to point to your local build.
Environment variables like JAVA_HOME and DATOMIC_URL may need to be customized per environment. Use placeholders in the mcp_config and replace at deployment time.
Monitor server logs for capabilities and tools list changes as you extend the MCP server with additional Datomic queries or transformations.

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