# Pixeltable Developer

A local MCP server that lets an agent scaffold app.py, apply tables to a catalog, insert rows and serve HTTP routes.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI · ★ 7
- Author: pixeltable
- License: Apache-2.0 · policy=link-only · description only; the file stays with the author
- Source: https://github.com/pixeltable/mcp-server-pixeltable-developer
- Updated: 2026-10-22
- HTML: https://affpapa.org/en/nevibecode/mcp/pixeltable-developer

## What it does

The server sits on top of the `pxt` CLI. An agent writes a single `app.py`, checks the catalog schema against it, applies updates, inserts rows, inspects what is stored, recomputes failed values and starts services. Every action goes through MCP tools, so a bad call comes back as a tool error the client can retry with fixed input.

You need `uv` first: the package lives on PyPI and `uvx` fetches it. Two variables are required — `PIXELTABLE_MCP_PROJECT_ROOT` pointing at the directory that holds `app.py`, and `PIXELTABLE_HOME` pointing at the Pixeltable catalog. Both paths are locked for the life of the process, and file arguments outside the project root get refused. The `pxt` daemon listens on port 22089 by default, and one daemon serves one project: run `pxt` for a second project at the same time and in-flight calls die with `RemoteDisconnected`. Point tests at a separate catalog, since the server writes to whichever one you hand it.

Setting `PIXELTABLE_MCP_ENABLE_UNSAFE=1` unlocks tools that execute arbitrary Python, install packages and read any file the process can reach. This is a beta developer tool running with your permissions. The same `app.py` works in the cloud, but that path wants `pxt login`, a `[[pixeltable.database]]` entry in `pixeltable.toml` and provider keys stored via `pxt secret set`. The server itself provisions nothing paid.

## Requirements
- Needs: Python and uv (commands run via uvx)
- Environment variables: `PIXELTABLE_MCP_PROJECT_ROOT`, `PIXELTABLE_HOME` — keys and tokens: ask the human for the values, never commit them or put them in shared files.

## Install

### Claude Code (native platform)

**Platform CLI**
```bash
claude mcp add mcp-server-pixeltable-developer -e PIXELTABLE_MCP_PROJECT_ROOT=<PIXELTABLE_MCP_PROJECT_ROOT> -e PIXELTABLE_HOME=<PIXELTABLE_HOME> -- uvx mcp-server-pixeltable-developer
```
Replace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from mcp-server-pixeltable-developer <command>

### Codex

**Platform CLI**
```bash
codex mcp add pixeltable-developer --env PIXELTABLE_MCP_PROJECT_ROOT=<PIXELTABLE_MCP_PROJECT_ROOT> --env PIXELTABLE_HOME=<PIXELTABLE_HOME> -- uvx mcp-server-pixeltable-developer
```
Replace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from mcp-server-pixeltable-developer <command>

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "pixeltable-developer": {
            "command": "uvx",
            "args": [
                "mcp-server-pixeltable-developer"
            ],
            "env": {
                "PIXELTABLE_MCP_PROJECT_ROOT": "<PIXELTABLE_MCP_PROJECT_ROOT>",
                "PIXELTABLE_HOME": "<PIXELTABLE_HOME>"
            }
        }
    }
}
```
Replace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from mcp-server-pixeltable-developer <command>

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "pixeltable-developer": {
            "type": "stdio",
            "command": "uvx",
            "args": [
                "mcp-server-pixeltable-developer"
            ],
            "env": {
                "PIXELTABLE_MCP_PROJECT_ROOT": "<PIXELTABLE_MCP_PROJECT_ROOT>",
                "PIXELTABLE_HOME": "<PIXELTABLE_HOME>"
            }
        }
    }
}
```
Replace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from mcp-server-pixeltable-developer <command>

### Gemini CLI

**Platform CLI**
```bash
gemini mcp add -e PIXELTABLE_MCP_PROJECT_ROOT=<PIXELTABLE_MCP_PROJECT_ROOT> -e PIXELTABLE_HOME=<PIXELTABLE_HOME> pixeltable-developer uvx mcp-server-pixeltable-developer
```
Replace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from mcp-server-pixeltable-developer <command>

## When to use it
- scaffold `app.py` with tables and computed columns
- diff the app schema against the live catalog and apply it
- insert rows and inspect what a table already holds
- recompute a column after editing its expression
- start a service and find its URL

## Example prompts
- Scaffold a Pixeltable app in `app.py` with a documents table and an embedding computed column.
- Show the schema diff between `app.py` and the `my_app` catalog, then apply it.
- Recompute the `embedding` column in `my_app/docs` — the values are stale.

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