Pilat/mcp Datalink

1# @pilat/mcp-datalink
2 
3MCP server for PostgreSQL, MySQL, and SQLite. Gives AI assistants secure database access via [Model Context Protocol](https://modelcontextprotocol.io).
4 
5```
6npx @pilat/mcp-datalink
7```
8 
9Works with Claude Desktop, Claude Code, Cursor, Cline, and any MCP-compatible client.
10 
11## Installation
12 
13Add to your MCP client config file (see [config locations](#config-file-locations) below):
14 
15```json
16{
17  "mcpServers": {
18    "datalink": {
19      "command": "npx",
20      "args": ["-y", "@pilat/mcp-datalink"],
21      "env": {
22        "DATALINK_ANALYTICS_URL": "postgresql://user:password@localhost:5432/analytics",
23        "DATALINK_ANALYTICS_READONLY": "true",
24 
25        "DATALINK_INVENTORY_URL": "mysql://user:password@localhost:3306/inventory",
26 
27        "DATALINK_CACHE_URL": "sqlite:///path/to/cache.db"
28      }
29    }
30  }
31}
32```
33 
34This creates three database connections: `analytics` (read-only), `inventory`, and `cache`.
35 
36| Variable | Description |
37|----------|-------------|
38| `DATALINK_{NAME}_URL` | Connection URL (creates database named `{name}`) |
39| `DATALINK_{NAME}_READONLY` | Set to `true` to block writes |
40| `DATALINK_{NAME}_MAX_TIMEOUT` | Max query timeout in ms (caps model requests) |
41 
42**Connection URL formats:**
43 
44```bash
45# PostgreSQL
46postgresql://user:password@localhost:5432/dbname
47postgresql://user:password@localhost:5432/dbname?sslmode=require
48 
49# MySQL
50mysql://user:password@localhost:3306/dbname
51mysql://user:password@localhost:3306/dbname?ssl=true
52 
53# SQLite
54sqlite:///path/to/database.db
55sqlite:///Users/me/data/app.sqlite
56sqlite://../relative/path/data.db
57```
58 
59### Environment Variable Substitution
60 
61URLs support `${VAR}` syntax to reference other environment variables:
62 
63```json
64{
65  "mcpServers": {
66    "datalink": {
67      "command": "npx",
68      "args": ["-y", "@pilat/mcp-datalink"],
69      "env": {
70        "DATALINK_MAIN_URL": "${DATABASE_URL}"
71      }
72    }
73  }
74}
75```
76 
77This allows reusing existing environment variables (like `DATABASE_URL` from your shell or `.env` file).
78 
79**Supported syntax:**
80 
81| Syntax | Description |
82|--------|-------------|
83| `${VAR}` | Expands to value of `VAR`, or keeps `${VAR}` if unset |
84| `${VAR:-default}` | Expands to value of `VAR`, or `default` if unset |
85 
86**Examples:**
87 
88```bash
89# Reference existing DATABASE_URL
90DATALINK_MAIN_URL="${DATABASE_URL}"
91 
92# Build URL from parts
93DATALINK_MAIN_URL="postgresql://${DB_USER}:${DB_PASS}@${DB_HOST}:5432/mydb"
94 
95# With default values
96DATALINK_MAIN_URL="postgresql://localhost:${DB_PORT:-5432}/mydb"
97```
98 
99### Config File Locations
100 
101| Client | Config file |
102|--------|-------------|
103| Claude Code | `~/.claude.json` (global) or `.mcp.json` (project) |
104| Claude Desktop (macOS) | `~/Library/Application Support/Claude/claude_desktop_config.json` |
105| Claude Desktop (Windows) | `%APPDATA%\Claude\claude_desktop_config.json` |
106| Cursor | `~/.cursor/mcp.json` or Settings → Features → MCP Servers |
107| Cline | `cline_mcp_settings.json` or VS Code settings `cline.mcpServers` |
108 
109## Tools
110 
111| Tool | Description |
112|------|-------------|
113| `list_databases` | List configured database connections |
114| `list_tables` | List tables with row counts |
115| `describe_table` | Get schema, indexes, foreign keys |
116| `query` | Run SELECT queries |
117| `execute` | Run INSERT/UPDATE/DELETE |
118| `explain` | Show query execution plans |
119 
120## Security
121 
122- Prepared statements only (no SQL injection)
123- Single statement per query (no chaining)
124- DDL blocked (no DROP, ALTER, TRUNCATE)
125- Readonly mode per connection
126- Output truncation (100 rows, 64KB max)
127- Query timeout: 30s default, model can request up to 10min, `MAX_TIMEOUT` caps it
128 
129## License
130 
131MIT
132