Connect to MotherDuck

Use this skill when establishing database connectivity from any application, script, or service to MotherDuck. Start here before running queries or loading data.

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 only 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.
• Start with one connection. Add pooling or read scaling only when real concurrent-read pressure exists.
• Use native DuckDB custom_user_agent where supported; for PG endpoint clients, prefer the client’s application_name setting when available.

Runtime Selection

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

Classify the workload first:

• Ad-hoc / exploration: one-shot, interactive, may be discarded. No artifact ships.
• Recurring / pipeline: scheduled, version-controlled, runs unattended. Code is checked into a repo.

Then resolve in this order, stopping at the first match:

1. MotherDuck MCP available + workload is ad-hoc → use the MCP tools (query, list_databases, list_tables, list_columns, search_catalog). No client to install. Stop here.
2. uv is installed (command -v uv) → run scripts via uv run --with "duckdb==<version>" script.py. Preferred for both ad-hoc scripts and pipelines because dependencies are declared inline and reproducible.
3. python3 + pip available → pip install "duckdb==<version>" inside a project-managed venv.
4. node + npm available → npm install @duckdb/node-api@<version>.
5. None of the above → install the DuckDB CLI: curl -s https://install.motherduck.com | env -u motherduck_token HOME="$install_home" sh. Pick $install_home as a writable, project-local path (for example ./.duckdb) rather than polluting the user’s home.

If the host project already declares a language (a pyproject.toml, package.json, or similar lockfile is present), follow that language even if the priority order would suggest otherwise. Do not introduce a second runtime alongside an existing one.

Before any install step, fetch https://motherduck.com/docs/duckdb-versions.json and pick the highest MotherDuck-supported DuckDB version. Pin that version explicitly in the install command. Latest upstream DuckDB is not automatically supported on MotherDuck.

Workflow

1. Choose one connection method and do not mix methods in the same application.
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 session_hint.

Open Next

• 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

• 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