OpenLink MCP Server for JDBC

A lightweight Java-based MCP (Model Context Protocol) server for JDBC built with Quakrus.

This server is compatible with Virtuoso DBMS and any other DBMS backend that has a JDBC driver.

Features

• Get Schemas: Fetch and list all schema names from the connected database.
• Get Tables: Retrieve table information for specific schemas or all schemas.
• Describe Table: Generate a detailed description of table structures, including:
  • Column names and data types
  • Nullable attributes
  • Primary and foreign keys
• Search Tables: Filter and retrieve tables based on name substrings.
• Execute Stored Procedures: _A Virtuoso-specific feature!_ Execute stored procedures and retrieve results.
• Execute Queries:
  • JSONL result format: Optimized for structured responses.
  • Markdown table format: Ideal for reporting and visualization.

Prerequisites

MCP server requires Java 21 or above.

Installation

Clone this repository:

git clone https://github.com/OpenLinkSoftware/mcp-jdbc-server.git  
cd mcp-jdbc-server

Environment Variables

Update your `.env` by overriding these defaults to match your preferences:

jdbc.url=jdbc:virtuoso://localhost:1111
jdbc.user=dba
jdbc.password=dba
jdbc.api_key=xxx

Configuration

For Claude Desktop users using Virtuoso and its JDBC driver:

Add the following to `claude_desktop_config.json`:

{
  "mcpServers": {
    "my_database": {
      "command": "java",
      "args": ["-jar", "/path/to/mcp-jdbc-server/MCPServer-1.0.0-runner.jar"],
      "env": {
        "jdbc.url": "jdbc:virtuoso://localhost:1111",
        "jdbc.user": "username",
        "jdbc.password": "password",
        "jdbc.api_key": "sk-xxx"
      }
    }
  }
}

For Claude Desktop users using another JDBC driver or a combination of drivers:

Add the following, edited to suit your local environment, to `claude_desktop_config.json`:

"jdbc": {
      "command": "java",
      "args": [
        "-cp",
        "/path/to/mcp-jdbc-server/MCPServer-1.0.0-runner.jar:/path/to/jdbc_driver1.jar:/path/to/jdbc_driverN.jar",
        "io.quarkus.runner.GeneratedMain"
      ],
      "env": {
        "jdbc.url": "jdbc:virtuoso://localhost:1111",
        "jdbc.user": "dba",
        "jdbc.password": "dba"
      }
    }

Use

Tools Provided

After successful installation, the following tools will be available to MCP client applications.

Overview

Detailed Description

• `jdbc_get_schemas`
  • Retrieve and return a list of all schema names from the connected database.
  • Input parameters:
    • `user` (string, optional): Database username. Defaults to `"demo"`.
    • `password` (string, optional): Database password. Defaults to `"demo"`.
    • `url` (string, optional): JDBC URL connection string.
  • Returns a JSON string array of schema names.

• `jdbc_get_tables`
  • Retrieve and return a list containing information about tables in a specified schema. If no schema is provided, uses the connection's default schema.
  • Input parameters:
    • `schema` (string, optional): Database schema to filter tables. Defaults to connection default.
    • `user` (string, optional): Database username. Defaults to `"demo"`.
    • `password` (string, optional): Database password. Defaults to `"demo"`.
    • `url` (string, optional): JDBC URL connection string.
  • Returns a JSON string containing table information (e.g., `TABLE_CAT`, `TABLE_SCHEM`, `TABLE_NAME`, `TABLE_TYPE`).

• `jdbc_filter_table_names`
  • Filters and returns information about tables whose names contain a specific substring.
  • Input parameters:
    • `q` (string, required): The substring to search for within table names.
    • `schema` (string, optional): Database schema to filter tables. Defaults to connection default.
    • `user` (string, optional): Database username. Defaults to `"demo"`.
    • `password` (string, optional): Database password. Defaults to `"demo"`.
    • `url` (string, optional): JDBC URL connection string.
  • Returns a JSON string containing information for matching tables.

• `jdbc_describe_table`
  • Retrieve and return detailed information about the columns of a specific table.
  • Input parameters:
    • `schema` (string, required): The database schema name containing the table.
    • `table` (string, required): The name of the table to describe.
    • `user` (string, optional): Database username. Defaults to `"demo"`.
    • `password` (string, optional): Database password. Defaults to `"demo"`.
    • `url` (string, optional): JDBC URL connection string.
  • Returns a JSON string describing the table's columns (e.g., `COLUMN_NAME`, `TYPE_NAME`, `COLUMN_SIZE`, `IS_NULLABLE`).

• `jdbc_query_database`
  • Execute a standard SQL query and return the results in JSON format.
  • Input parameters:
    • `query` (string, required): The SQL query string to execute.
    • `user` (string, optional): Database username. Defaults to `"demo"`.
    • `password` (string, optional): Database password. Defaults to `"demo"`.
    • `url` (string, optional): JDBC URL connection string.
  • Returns query results as a JSON string.

• `jdbc_query_database_md`
  • Execute a standard SQL query and return the results formatted as a Markdown table.
  • Input parameters:
    • `query` (string, required): The SQL query string to execute.
    • `user` (string, optional): Database username. Defaults to `"demo"`.
    • `password` (string, optional): Database password. Defaults to `"demo"`.
    • `url` (string, optional): JDBC URL connection string.
  • Returns query results as a Markdown table string.

• `jdbc_query_database_jsonl`
  • Execute a standard SQL query and return the results in JSON Lines (JSONL) format (one JSON object per line).
  • Input parameters:
    • `query` (string, required): The SQL query string to execute.
    • `user` (string, optional): Database username. Defaults to `"demo"`.
    • `password` (string, optional): Database password. Defaults to `"demo"`.
    • `url` (string, optional): JDBC URL connection string.
  • Returns query results as a JSONL string.

• `jdbc_spasql_query`
  • _A Virtuoso-specific feature!_
  • Execute a SPASQL (SQL/SPARQL hybrid) query return results.
  • Input parameters:
    • `query` (string, required): The SPASQL query string.
    • `max_rows` (number, optional): Maximum number of rows to return. Defaults to `20`.
    • `timeout` (number, optional): Query timeout in milliseconds. Defaults to `30000` (i.e., 30 seconds).
    • `user` (string, optional): Database username. Defaults to `"demo"`.
    • `password` (string, optional): Database password. Defaults to `"demo"`.
    • `url` (string, optional): JDBC URL connection string.
  • Returns the result from the underlying stored procedure call (e.g., `Demo.demo.execute_spasql_query`).

• `jdbc_sparql_query`
  • _A Virtuoso-specific feature!_
  • Execute a SPARQL query and return results.
  • Input parameters:
    • `query` (string, required): The SPARQL query string.
    • `format` (string, optional): Desired result format. Defaults to `'json'`.
    • `timeout` (number, optional): Query timeout in milliseconds. Defaults to `30000` (i.e., 30 seconds).
    • `user` (string, optional): Database username. Defaults to `"demo"`.
    • `password` (string, optional): Database password. Defaults to `"demo"`.
    • `url` (string, optional): JDBC URL connection string.
  • Returns the result from the underlying function call (e.g., `"UB".dba."sparqlQuery"`).

• `jdbc_virtuoso_support_ai`
  • _A Virtuoso-specific feature!_
  • Utilizes a Virtuoso-specific AI Assistant function, passing a prompt and optional API key.
  • Input parameters:
    • `prompt` (string, required): The prompt text for the AI function.
    • `api_key` (string, optional): API key for the AI service. Defaults to `"none"`.
    • `user` (string, optional): Database username. Defaults to `"demo"`.
    • `password` (string, optional): Database password. Defaults to `"demo"`.
    • `url` (string, optional): JDBC URL connection string.
  • Returns the result from the AI Support Assistant function call (e.g., `DEMO.DBA.OAI_VIRTUOSO_SUPPORT_AI`).

Basic Use & Troubleshooting

MCP Inspector Connecting to Virtuoso's ODBC Driver

For basic MCP client use and troubleshooting, use the MCP Inspector as follows:

1. Install the MCP Inspector:

npm install -g @modelcontextprotocol/inspector

2. Start the inspector:

npx @modelcontextprotocol/inspector java -jar /path/to/mcp-jdbc-server/MCPServer-1.0.0-runner.jar

Access the URL returned by the inspector to troubleshoot MCP server interactions.

MCP Inspector Connecting to additional Drivers

For basic MCP client use and troubleshooting, use the MCP Inspector as follows:

1. Install the JDBC Driver(s), ensuring their JAR files are registered with the host operating system's Java Virtual Machine (JVM) via `$CLASSPATH`. For instance:

export CLASSPATH=$CLASSPATH:/path/to/driver1.jar:/path/to/driver2.jar:/path/to/driverN.jar

2. Start the inspector using the following command-line arguments:

npx @modelcontextprotocol/inspector java -cp MCPServer-1.0.0-runner.jar:/path/to/driver1.jar:/path/to/driver2.jar:/path/to/driverN.jar io.quarkus.runner.GeneratedMain

Use Example based on Oracle and Informix Drivers

0. Assuming the following JDBC Driver information:

jdbc:oracle:thin:@:[port]:

jdbc:informix-sqli://:/:=

1. Install the Oracle (`ojdbc17.jar`) and/or Informix (`jdbc-15.0.0.1.1.jar`) JDBC Drivers, and ensure their JAR files are registered with the host operating system's Java Virtual Machine (JVM) via `$CLASSPATH`. For instance:

export CLASSPATH=$CLASSPATH:/path/to/Java/Extensions/jdbc-15.0.0.1.1.jar
    export CLASSPATH=$CLASSPATH:/path/to/Java/Extensions/ojdbc17.jar

2. Start the inspector using the following command-line arguments:

npx @modelcontextprotocol/inspector java -cp MCPServer-1.0.0-runner.jar:/path/to/Java/Extensions/ojdbc17.jar:/path/to/Java/Extensions/jdbc-15.0.0.1.1.jar io.quarkus.runner.GeneratedMain

3. Access the URL returned by the inspector and then use the `jdbc_execute_query` operation to query the target database, by providing actual values for the following input field templates: