for developers
Builder can leverage multiple external tools when designing your Project with Builder. All integrations can be access on the Integrations page.
When running Builder projects you can configure local MCP servers to run as child process. This enables Builder to access local databases, development tools, and internal services.
Connecting to a local MCP server works as follows:
- Builder looks for a local
mcp.jsonfile. - Each server mentioned in the configuration file is spawned as a child process.
- Tools are registered with the naming pattern:
mcp__servername__toolname. - Builder automatically uses these tools when relevant.
- Processes are cleaned up when the session ends.
Your mcp.json file should live within the root directory and have the following format:
{
"mcpServers": {
"database": {
"type": "stdio",
"command": "npx",
"args": ["-y", "@modelcontextprotocol/server-postgres", "${DATABASE_URL}"],
"env": {
"DATABASE_URL": "postgresql://localhost:5432/mydb"
}
}
}
}| Field | Required? | Description | Example |
|---|---|---|---|
| Yes | Connection type (always |
|
| Yes | Command to execute the server |
|
| No | Arguments passed to the execution command |
|
| No | Environment variables for the server |
|
| No | Path to load environment variables from |
|