QuestDB MCP Server

An MCP server that connects coding agents (Claude Code, Codex, Cursor, OpenCode …) to a

running QuestDB Web Console. The agent gets tools to create notebook

cells, run queries, and build charts. Every action executes in the

browser against your already-established QuestDB session.

Setup

Quick setup (recommended)

The interactive wizard detects your installed coding agents and

writes the bridge into each one's MCP config:

npx @questdb/mcp-server-questdb setup

It walks you through two steps:

1. Pick agents: multi-select from the ones it detects (Claude Code,

Codex, Cursor, OpenCode, Gemini CLI).

2. Review settings: optionally override `CONSOLE_ORIGIN` and

`MCP_BRIDGE_PORT`; press Enter to keep the defaults.

The wizard pins each agent's config to the bridge version that ran it. Your

QuestDB Web Console expects a specific bridge version. If you're on an older

console, run the matching version: `npx @questdb/mcp-server-questdb@ setup`. The config it writes will launch that same version. (When unsure, pair first; on a version mismatch the agent is told which version to switch to.)

Manual setup

Or add it to your MCP client's config by hand (e.g. `~/.claude/.mcp.json`):

{
  "mcpServers": {
    "questdb": {
      "command": "npx",
      "args": ["-y", "@questdb/mcp-server-questdb"]
    }
  }
}

Environment variables

Commands

Your MCP client runs the bridge for you via the config above, so you

rarely invoke it by hand. When you do:

An unknown command exits non-zero with a short error. Pin a version with

`npx @questdb/mcp-server-questdb@0.3.0 start`. (Installed on your `PATH`, the

executable is named `mcp-server-questdb`.)

Pairing

Before any notebook / chart / SQL tool works, your browser has to pair

with the bridge. The agent drives the flow.

When the agent needs to pair, it calls `get_pairing_credentials` and

shows you both:

• A one-click deep link — open it in the tab showing your Web Console.
• A WebSocket URL + token — paste into the MCP pill at the bottom

of the Web Console if the deep link doesn't land in the right tab.

Either path lands you on a consent prompt. Accept it and the agent's

next tool call goes through.

Each bridge run generates a fresh port and pairing token, held only in

memory. On restart the old credentials stop working — the agent will

surface new ones the next time it needs to pair.

Logs

The bridge writes to stderr and to a log file. Tail the newest:

tail -F "$(ls -t /tmp/questdb-mcp-bridge/*.log | head -1)"

At default `INFO`:

2026-05-15T12:29:27.142Z [INFO] tool_call: run_query
2026-05-15T12:29:27.318Z [INFO] tool_result: run_query ok
2026-05-15T12:29:28.011Z [ERROR] tool_result: update_cell internal_error timeout after 15000ms

At `DEBUG` (full payloads as continuation lines):

2026-05-15T12:29:27.142Z [INFO] tool_call: run_query
2026-05-15T12:29:27.142Z [DEBUG]   args: {"query":"SELECT count() FROM trades"}
2026-05-15T12:29:27.318Z [INFO] tool_result: run_query ok
2026-05-15T12:29:27.318Z [DEBUG]   content: [{"type":"text","text":"..."}]

License

Apache-2.0.