motherduck-connect

Connect to MotherDuck

Source Of Truth

• Prefer current MotherDuck connection, attach-mode, read-scaling, and multithreading docs.
• If the MotherDuck MCP ask_docs_question tool is available, use it first for current connection behavior.
• When it is unavailable, verify guidance against the public docs before making firm claims about connection strings, token types, or read-scaling behavior.

Default Posture

• Start with the PG endpoint (MotherDuck's Postgres-compatible endpoint) for backend applications, BI tools, and serverless runtimes that want PostgreSQL wire compatibility.
• For BI tools, treat the PG endpoint as the compatibility path for Power BI and Tableau Cloud when current docs list them as supported.
• Use the native DuckDB API when you need local files, hybrid local/cloud execution, or direct DuckDB control.
• Use md: workspace connections for multi-database exploration, bootstrap flows, and temporary validation environments.
• Reuse an existing connection, connector, or environment-managed token when the user's context already provides one; do not ask for secrets that can be discovered from the active workspace. When only the MotherDuck MCP server is connected and a one-off local session needs credentials, get_short_lived_token returns a temporary token and endpoint details; pass it through the process environment and never write it to files, code, or logs. Deployed services still need a service-account token.
• Start with one connection. Add pooling or read scaling only when real concurrent-read pressure exists.
• For services that should fail over instead of blocking while a Duckling starts, bound native md: connects with connection_timeout (md:my_db?connection_timeout=30s, MOTHERDUCK_CONNECTION_TIMEOUT, or SET motherduck_connection_timeout = '30s' before the first ATTACH 'md:'). It applies to DuckDB clients with the MotherDuck extension, not the PG endpoint or Wasm. Without it, only network retries are bounded.
• Use native DuckDB custom_user_agent where supported; for PG endpoint clients, prefer the client's application_name setting when available. The tag shows per query in the Duckling Overview, which makes it the quickest way to see which workload is using a Duckling.

Runtime Selection

Pick the connection method (above) and the runtime separately. The runtime is what actually executes queries: MotherDuck MCP, the MotherDuck CLI, a Python or Node process, or the DuckDB CLI.

For answer, review, or planning requests, inspect the available runtimes and recommend a path without installing anything. Install or configure a runtime only when the user asks to connect, build, or change the application.

Reuse the project’s language, dependencies, and working connection. Prefer MCP for chat-only exploration and the MotherDuck CLI for file-shaped Dive/Flight work or large output. For application code, use its existing runtime; choose a new runtime only when none is established.

Before installing a DuckDB client, check https://motherduck.com/docs/duckdb-versions.json and pin a MotherDuck-supported version. Keep an existing compatible pin unless the task requires an upgrade. See the runtime reference for installation examples.

Workflow

1. Choose the connection path for the workload; keep ingestion and serving paths distinct when their needs differ.
2. Put the MotherDuck token in environment-managed secrets, not in source code.
3. Establish the connection with explicit SSL settings where required.
4. Verify the connection with SELECT 1 AS connected and then list reachable tables.
5. If the workload is read-heavy and concurrent, evaluate read scaling and a stable session_name per end user.

References

Read only the reference sections needed for the current task.

• Read references/CONNECTION_GUIDE.md for connection-method selection, PG endpoint and native DuckDB examples, token handling, read scaling, attach modes, and common failure modes
• Read references/RUNTIME_SELECTION.md for the MCP-vs-Python-vs-Node-vs-CLI decision tree, detection commands, install snippets, and the DuckDB version-pinning workflow

Related Skills

Load related skills only for missing capabilities; reuse established context.

• motherduck-explore for discovering databases, tables, columns, and shares after the connection is established
• motherduck-query for executing DuckDB SQL against the connected databases
• motherduck-duckdb-sql for DuckDB syntax and function lookup support
• motherduck-rest-api for control-plane admin operations; those use MOTHERDUCK_ADMIN_TOKEN, which is never used for database connections
• motherduck-cli for terminal queries and file-oriented Dive/Flight authoring