Oracle Database MCP Server
This MCP server enables LLMs like GitHub Copilot and Claude to securely query Oracle databases using read-only SQL operations through the Model Context Protocol.
Core Capabilities:
Execute Read-Only SQL Queries - Run SELECT statements with configurable limits on maximum rows (default 1000) and query timeouts (default 30 seconds), receiving results with column names and execution metrics
Schema Introspection - List all accessible tables or retrieve detailed column information (names, types, metadata) for specific tables using
get_database_schemaSecurity - Operates exclusively with dedicated read-only database users having only SELECT privileges, with resource limits to prevent exhaustion
Connection Management - Efficient Oracle connection pooling with configurable pool sizes for optimal performance
Audit Logging - Comprehensive logging of all queries with execution metrics in JSON format for monitoring and review
No Oracle Client Required - Uses Thin Mode with pure JavaScript driver, no Oracle Instant Client installation needed
stdio Transport - Communicates via standard I/O through MCP protocol without requiring an HTTP server
Integration Options:
VS Code with GitHub Copilot for natural language database queries
Claude Desktop for direct AI assistant integration
Other MCP-compatible clients
Built-in test client for local verification
Example Use Cases: Ask "What tables are in the database?" for schema exploration, "Show me the top 10 customers by revenue" for data analysis, or "How many active users do we have?" for reporting.
Enables GitHub Copilot to execute read-only SQL queries against Oracle databases, providing schema exploration and data retrieval capabilities through natural language prompts.
Click on "Install Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type
@followed by the MCP server name and your instructions, e.g., "@Oracle Database MCP Servershow me the top 10 customers by total orders"
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
Oracle Database MCP Server
A Model Context Protocol (MCP) server that enables GitHub Copilot and other LLMs to execute read-only SQL queries against Oracle databases.
⚠️ Breaking Changes in v2.0
DATE, TIMESTAMP, TIMESTAMP WITH TIME ZONE, and TIMESTAMP WITH LOCAL TIME ZONE columns are now returned as formatted strings (YYYY-MM-DD HH:mm:ss) instead of raw JavaScript Date objects.
The timezone is controlled by ORACLE_TIMEZONE (IANA name). If unset it falls back to the server's system timezone, which may differ across machines.
Action required — add ORACLE_TIMEZONE to your .env or MCP env block:
ORACLE_TIMEZONE=UTC # or e.g. America/ChicagoRelated MCP server: OracleDB MCP Server
Table of Contents
📦 Installation
From npm (quickest)
npm install -g mcp-oracle-databaseBuild from Source
git clone https://github.com/tannerpace/mcp-oracle-database.git
cd mcp-oracle-database
npm install
npm run buildmacOS Apple Silicon (M1/M2/M3/M4) with no Oracle yet? See the macOS Setup Guide to spin up Oracle XE 21c locally via Colima.
🔌 Configure VS Code
Create .vscode/mcp.json in your workspace (or add to your global MCP config).
Option A — From Source
{
"servers": {
"oracleDatabase": {
"type": "stdio",
"command": "node",
"args": ["/absolute/path/to/mcp-oracle-database/dist/server.js"],
"env": {
"ORACLE_CONNECTION_STRING": "localhost:1521/XE",
"ORACLE_USER": "system",
"ORACLE_PASSWORD": "OraclePwd123",
"ORACLE_TIMEZONE": "UTC",
"ORACLE_POOL_MIN": "2",
"ORACLE_POOL_MAX": "10",
"QUERY_TIMEOUT_MS": "30000",
"MAX_ROWS_PER_QUERY": "1000",
"ENFORCE_READ_ONLY_QUERIES": "true",
"MCP_MAX_RESPONSE_CHARS": "50000",
"MCP_MAX_ROWS_IN_RESPONSE": "200",
"MCP_MAX_STRING_LENGTH": "500"
}
}
}
}Replace /absolute/path/to/mcp-oracle-database with the real path on your machine (e.g. /Users/yourname/GITHUB/mcp-oracle-database).
Option B — From npm Global Install
{
"servers": {
"oracleDatabase": {
"type": "stdio",
"command": "mcp-database-server",
"env": {
"ORACLE_CONNECTION_STRING": "localhost:1521/XE",
"ORACLE_USER": "your_user",
"ORACLE_PASSWORD": "your_password",
"ORACLE_TIMEZONE": "UTC",
"ORACLE_POOL_MIN": "2",
"ORACLE_POOL_MAX": "10",
"QUERY_TIMEOUT_MS": "30000",
"MAX_ROWS_PER_QUERY": "1000",
"ENFORCE_READ_ONLY_QUERIES": "true",
"MCP_MAX_RESPONSE_CHARS": "50000",
"MCP_MAX_ROWS_IN_RESPONSE": "200",
"MCP_MAX_STRING_LENGTH": "500"
}
}
}
}After saving, reload VS Code and open a Copilot chat in Agent mode. Try:
"What tables are in the database?"
"Describe the HELP table"
"Show me 5 rows from the HELP table"Optional: Create a Read-Only User
Using SYSTEM is fine for local testing. For any real database, use a dedicated read-only user:
-- Connect: sqlplus system/OraclePwd123@localhost:1521/XEPDB1
CREATE USER readonly_user IDENTIFIED BY secure_password;
GRANT CREATE SESSION TO readonly_user;
GRANT SELECT ANY TABLE TO readonly_user;
-- Or restrict to specific tables:
-- GRANT SELECT ON myschema.orders TO readonly_user;
-- GRANT SELECT ON myschema.customers TO readonly_user;Then update your .env or MCP config:
ORACLE_CONNECTION_STRING=localhost:1521/XEPDB1
ORACLE_USER=readonly_user
ORACLE_PASSWORD=secure_passwordFeatures
🔒 Read-only access — Dedicated read-only database user for security
📡 stdio transport — No HTTP server; communicates via standard input/output
⚡ Connection pooling — Efficient Oracle connection management
📊 Schema introspection — Query table and column information
🔍 Advanced schema discovery — 5 specialized tools for tables, relationships, and data patterns
💾 In-memory caching — LRU cache with 5-minute TTL for fast repeated access
📝 Audit logging — All queries logged with execution metrics
⏱️ Timeout protection — Prevents long-running queries
🛡️ Result limits — Configurable row limits to prevent memory issues
🍎 No Oracle Client needed — Uses node-oracledb Thin Mode (pure JS, works on Apple Silicon)
Architecture
GitHub Copilot / LLM
↓ (MCP Protocol)
MCP Client (spawns process)
↓ (JSON-RPC over stdio)
MCP Server (Node.js)
↓ (node-oracledb Thin Mode)
Oracle Database (read-only user)Available Tools
Core Tools
query_database
Execute read-only SQL SELECT queries.
{
"query": "SELECT table_name FROM user_tables FETCH FIRST 10 ROWS ONLY",
"maxRows": 10
}get_database_schema
Get a table list or column details for a specific table.
{ "tableName": "ORDERS" }Schema Discovery Tools
Tool | Purpose | Cached |
| All accessible tables with metadata & optional row counts | ✅ |
| Column types, constraints, primary/foreign keys | ✅ |
| Foreign key relationships in JSON | ✅ |
| Sample values to understand data formats | ❌ |
| Find related tables by FK, naming, shared columns | ❌ |
📖 See Schema Discovery Documentation for full details and examples.
Example Copilot Prompts
"List all tables in the database"
"Describe the ORDERS table and its relationships"
"How many active users are there?"
"What are the top 5 products by sales this month?"
"Show me recent transactions for customer ID 12345"Configuration Reference
All settings can go in .env or as env keys in your VS Code MCP config.
# Oracle Database Connection
ORACLE_CONNECTION_STRING=localhost:1521/XE # host:port/service
ORACLE_USER=system
ORACLE_PASSWORD=OraclePwd123
# Timezone (REQUIRED for consistent date/timestamp output)
ORACLE_TIMEZONE=UTC # IANA timezone, e.g. America/New_York
# Connection Pool
ORACLE_POOL_MIN=2
ORACLE_POOL_MAX=10
# Query Safety
QUERY_TIMEOUT_MS=30000 # max query time in ms
MAX_ROWS_PER_QUERY=1000 # max rows Oracle will fetch
MAX_QUERY_LENGTH=50000 # max SQL length in chars
ENFORCE_READ_ONLY_QUERIES=true # reject non-SELECT statements
# MCP Response Limits
MCP_MAX_RESPONSE_CHARS=50000 # hard cap on total response size
MCP_MAX_ROWS_IN_RESPONSE=200 # max rows per tool call response
MCP_MAX_STRING_LENGTH=500 # max chars per string field
# Logging
LOG_LEVEL=info
ENABLE_AUDIT_LOGGING=true
ENABLE_FILE_LOGGING=true
LOG_DIR=./logs
NODE_ENV=developmentLarge schemas: If your database has 500+ tables, raise
MCP_MAX_RESPONSE_CHARSto100000.
Development
Scripts
npm run build # Compile TypeScript → dist/
npm run dev # Watch mode compilation
npm run clean # Remove dist/
npm run typecheck # Type-check without compiling
npm start # Start MCP server (requires build first)
npm run test-client # Core tool tests against live Oracle DB
npm run test-discovery # Schema discovery tool testsProject Structure
mcp-oracle-database/
├── src/
│ ├── server.ts # MCP server entry point
│ ├── client.ts # Core test client
│ ├── test-discovery.ts # Discovery tools test client
│ ├── config.ts # Zod-validated configuration
│ ├── database/
│ │ ├── oracleConnection.ts # Connection pool manager
│ │ ├── queryExecutor.ts # Query execution + safety checks
│ │ └── types.ts
│ ├── tools/
│ │ ├── queryDatabase.ts # query_database tool
│ │ ├── getSchema.ts # get_database_schema tool
│ │ └── discovery/ # 5 schema discovery tools + cache
│ └── utils/
│ ├── logger.ts # Lightweight file + console logger
│ └── responseFormatter.ts # MCP response size management
├── dist/ # Compiled output (git-ignored)
├── .env # Your credentials (git-ignored)
├── .env.example # Template
└── package.jsonSecurity Considerations
Read-Only User — Database user should have only SELECT privileges in production
SQL Safety — The server trusts the LLM to generate valid SQL; the read-only user is the safety net
Query Limits — Row count and timeout limits prevent resource exhaustion
Audit Logging — All queries logged with timestamps for review
Local First — Designed to run on your machine; can still connect to remote databases
Troubleshooting
Connection failed
Error: ORA-12545: Connect failed because target host or object does not existIs Oracle running?
docker ps | grep oracle-xeCheck the port:
docker psshould show0.0.0.0:1521->1521/tcpTry
localhost:1521/XEfor SYSTEM,localhost:1521/XEPDB1for other users
Wrong service name
Service | Use for |
| SYSTEM user, DBA operations |
| Regular application users |
Permission denied
Error: ORA-00942: table or view does not existGRANT SELECT ANY TABLE TO your_user;Response too large
Response for tool 'listTables' exceeded MCP_MAX_RESPONSE_CHARSMCP_MAX_RESPONSE_CHARS=100000Colima / Docker issues (macOS)
See macOS Setup Guide — Troubleshooting.
Thin Mode note
This project uses node-oracledb Thin Mode — a pure JavaScript driver that requires no Oracle Instant Client. It works on all platforms including Apple Silicon Macs.
Documentation
📚 Guides:
macOS Setup Guide — Local Oracle XE setup on Apple Silicon
Schema Discovery Guide — Advanced schema introspection tools
Schema Discovery Quick Reference — Cheat sheet for all discovery tools
Schema Discovery Examples — MCP message examples
VS Code Integration Guide — Set up with GitHub Copilot
Claude Desktop Integration Guide — Set up with Claude Desktop
MCP Integration Guide — MCP protocol deep dive
Architecture Overview — System architecture diagram
Logging Configuration — Logging setup and configuration
📝 Custom Instructions:
.github/copilot-instructions.md— Project-wide Copilot instructions.github/instructions/— Language-specific coding guidelines
Licensing
This project is licensed under the GNU Affero General Public License v3.0 (AGPL-3.0).
You are free to use, modify, and distribute this software under the terms of the AGPL-3.0. Any modified version deployed as a network service must make its source code available to users of that service.
See LICENSE.md for the full license text.
Oracle is a registered trademark of Oracle Corporation. This project is not affiliated with, endorsed by, or sponsored by Oracle Corporation.
Maintenance
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