Grain SQL

Local

grain.toolsDatabases3Updated 2d ago

About Grain SQL

Grain SQL is a VS Code SQL workspace that also lets AI agents query configured databases. It keeps query activity visible in the results panel and gives agents read-only access by default.

Key features

01Run SQL from editor files
02Manage and test connection profiles
03Sortable and filterable results grid
04Export results as CSV, TSV, or JSON
05Read-only agent queries over MCP

Use cases

01Inspect database schemas from an editor
02Review an agent's database queries and results
03Export full query results for further use

MCP support

Grain exposes configured database connections to Claude Code, Cursor, and GitHub Copilot over MCP. MCP must be enabled in settings; agent access is read-only by default and queries appear in the results panel.

Configuration

Local server config is the same for every client. Copy it into your client’s MCP config file.

mcp.json · Universal config

{
  "mcpServers": {
    "pattrnlabs-grain": {
      "command": "npx",
      "args": [
        "-y",
        "grain-tools"
      ],
      "env": {
        "GRAIN_CONNECTIONS": "<GRAIN_CONNECTIONS>",
        "GRAIN_MCP_SAFE_MODE": "<GRAIN_MCP_SAFE_MODE>",
        "GRAIN_MAX_ROWS": "<GRAIN_MAX_ROWS>"
      }
    }
  }
}

Run commandnpx -y grain-tools

Environment variables to set

GRAIN_CONNECTIONSSecretJSON array of Grain connection profiles for headless use.

GRAIN_MCP_SAFE_MODESet to false to allow mutating SQL. Defaults to true.

GRAIN_MAX_ROWSMaximum rows returned by query tools. Defaults to 10000.

Local servers need a runtime on your machine (e.g. Node.js 18+). Config file locations differ by client; see your client’s docs.

Packages

npmgrain-tools0.10.39stdio

Tools

No tool list yet

Local servers expose tools only once running on your machine, and the maintainer has not provided a tool list.

Details

From the project README

Grain

A fast SQL workspace for VS Code, and for the AI agents you work with.

Docs · Changelog · Report a bug · Ask a question

Run SQL from any .sql file with Ctrl+Enter and get the results in a sortable grid inside VS Code. Passwords stay in your OS keychain, and Grain has no hosted service.

Run a query in Grain

Quick start

Install Grain from the VS Code Marketplace or Open VSX (for Cursor, Windsurf, and VSCodium).
Open a folder in VS Code. Grain adds its demo files there.
Open the Grain panel and click Try the Demo.
Put your cursor in any query in the file that opens and press Ctrl+Enter (Cmd+Enter on macOS).

The demo reads two CSV files through Grain's built-in DuckDB connection, so there's nothing to set up. To query your own database, run Grain: Manage Connections, add a profile, and test it before you save.

The Grain panel, annotated

If Grain is useful to you, a star on this repo helps other developers find it.

Use Grain from an AI agent

Grain can serve your database connections to Claude Code, Cursor, and GitHub Copilot over MCP. Agents get read-only access by default, and every query an agent runs shows up in your Grain results panel, so you can see exactly what it did.

MCP is off until you turn on grain.mcpEnabled in settings. Setup steps for each client are in the MCP docs, and example prompts are in examples/agents/.

Features

Feature	What it does
Run from the editor	`Ctrl+Enter` runs the file; Run Query Under Cursor runs one statement; Run Query in New Tab keeps the previous result
Non-blocking queries	Queries run in a background process, so a slow query doesn't freeze VS Code
Connection manager	Create, test, and switch database profiles without editing JSON
Result grid	Sort, filter, and resize columns, see each column's SQL type, copy a selection as TSV
Full export	The grid shows the first 500 rows; export re-runs the query and writes every row to CSV, TSV, or JSON
Agent access over MCP	Claude Code, Cursor, and Copilot can query your connections; their results land in your panel
Remote setups	Works over WSL, dev containers, GitHub Codespaces, and Remote - SSH

Supported databases

Relational databases	PostgreSQL	MySQL	SQL Server	SQLite
Data warehouses	Snowflake	BigQuery
Query engines & lakehouses	Trino / Presto	DuckDB
Search	Elasticsearch

Through Trino or Presto you can query your cluster's Iceberg, Delta Lake, and Hive tables. DuckDB queries local CSV and Parquet files directly.

PostgreSQL and Trino / Presto are bundled with the extension. The others load their driver on first use, and if a driver is missing, Grain tells you what to install.

Need another database? Request a connector. Requests with the most 👍 get built first.

Examples

Runnable queries for Postgres, MySQL, Elasticsearch, and DuckDB, plus agent prompts. Open any .sql file with Grain installed and press Ctrl+Enter.

Privacy

Your SQL, results, and passwords stay on your machine. Passwords are stored in VS Code Secret Storage, backed by your OS keychain, and never in a settings file.
Agents are read-only by default. With grain.mcpSafeMode on (the default), agents can only run SELECT, SHOW, DESCRIBE, EXPLAIN, WITH, and metadata queries. Agents can't read stored passwords or change saved connections.
Telemetry is anonymous. Grain sends usage data that never includes SQL, results, credentials, hostnames, or schema names. Turn it off with grain.telemetry.enabled.

FAQ

Is Grain open source?
No. Grain is closed-source. This repo holds the issue tracker, docs, and examples.

Which databases does it support?
The nine listed above. To ask for another one, request a connector.

Do my queries or passwords leave my machine?
No. There's no Grain server. Queries go straight from VS Code to your database, and passwords stay in your OS keychain. See Privacy for what the anonymous telemetry does and doesn't include.

How do I connect Claude Code or Cursor?
Turn on grain.mcpEnabled, then follow the steps for your client in the MCP docs.

Why does my database show a driver error?
Some connectors load their driver on first use. The error message names what to install. If it's still failing after that, file a bug report with the Output panel logs (View → Output → Grain).

Getting help

Bug: file a bug report
Feature idea: file a feature request
New database: request a connector
Question: check the FAQ and docs, then ask a question

We don't have a fixed roadmap yet. What we build next depends a lot on what people ask for here, especially connector requests. See CONTRIBUTING.md for how to file a good issue.

Star History

License

Grain is closed-source. See LICENSE.

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