Krita Codex MCP Server

Krita Codex MCP Server

Control Krita from OpenAI Codex through a secure local Model Context Protocol (MCP) server for Windows.

PyPI package · GitHub releases · Windows installation guide

A Windows-first local MCP server that lets Codex inspect and control Krita through a small, authenticated bridge. The MCP process uses STDIO. The Krita Python plugin listens only on 127.0.0.1, validates a shared bearer token, and dispatches every Krita API call to Qt's main thread.

This repository is a Windows-first integration with a capability-based runtime compatibility check. Krita 5.3.2.1 is a tested build, not a hard version requirement. The server deliberately exposes a small set of cohesive tools instead of a large collection of micro-tools:

Codex -> local STDIO MCP process -> authenticated 127.0.0.1 HTTP bridge
      -> queued, timeout-aware Qt main-thread dispatch -> Krita Python API

The bridge has no arbitrary Python execution tool and no direct pixel painting fallback. Actual painting, shapes, replacement fills and correction filters go through native Krita actions or stroke APIs. If the running Krita build lacks a feature, krita_state and krita_document(action="compatibility") report the affected tools. Calling that feature returns a structured error; the bridge never silently switches to a different rendering backend.

Quick start

This requires a Windows Krita build that passes the live compatibility check and uv/uvx on PATH. Close Krita, make sure the allowed directory already exists, and install the current release from PyPI:

uvx --from "krita-codex-mcp==0.2.0" `
  krita-codex-install install `
  --allowed-root "C:\Krita Work"

Then use this order for a real Krita session:

1. Enable Krita Codex Bridge in Krita's Python Plugin Manager.
2. Restart Krita so the installed plugin and shared protocol package are loaded together.
3. Run the same version's krita-codex-install check and require either Ready for productive use. or the explicit limited-mode success message.
4. Preview the checkout-free, exactly version-pinned uvx Codex block with krita-codex-install codex-config.
5. Apply it only after explicit confirmation, restart Codex, verify krita_state and krita_preview, and only then start normal work.

Install and update never close Krita. If the authenticated bridge is running, replacement is rejected before any installed files are changed and Krita must be closed manually. A busy local bridge port also stops the installer before replacement begins.

For a personal installation, use the user-level C:\Users\<you>\.codex\config.toml. This is the recommended option because the server is then available to all local Codex tasks and Git worktrees. The generated block uses uvx, has no checkout cwd, and pins the same exact distribution version as the installed plugin. The installer only changes that file after showing the full preview and receiving explicit confirmation. Unmarked or conflicting Krita entries are never overwritten. Never commit personal configuration. See the Windows installation guide for details.

The preflight checks local configuration, the complete installed hash manifest, wheel/plugin/ protocol versions, loopback port, authentication and the running Krita capability profile. The running plugin reports the distribution, protocol and Krita versions without adding an MCP tool. The check creates a disposable document, verifies a new paint layer, native drawing, Undo/Redo, transactional reparenting, direct PNG preview bytes and temporary KRA/PNG output beneath an allowed root. It restores the previously active document and removes every temporary file.

An unknown Krita version is accepted when all critical capabilities pass. Missing optional features produce limited warnings naming the affected MCP tools; missing projection, persistence, stable layer-tree or document-lifecycle APIs remain critical. The same structured report is available to Codex through krita_state, so it can avoid unavailable operations.

Capabilities and Krita limits

The current release supports native preset-backed painting and shapes, persistent document and layer editing, selections, color operations, KRA/PNG output, and Unity-oriented animation, tileset and named-region packages. Preview and asset operations return PNG images directly to the MCP caller. Re-export preserves Unity .meta sidecars for stable generated filenames.

The tested Krita 5.3.2.1 build imposes several safety limits. Other builds are evaluated at runtime and may report different available features:

• Free layer scale, rotate, shear and crop operations are not native Undo commands. The bridge creates a hidden backup layer and blocks a second direct transform until the KRA is saved, closed and reopened. checkpoint_reopen=true can perform that round trip automatically.
• Transform masks are limited to three per open document. Same-session mask mutation/removal and mixing mask and direct transform backends are blocked until Krita restarts.
• Node.paintLine requires integer QPoint values, so incoming canvas coordinates are rounded at the native API boundary.
• PNG export temporarily enables Krita batch mode so no format dialog can block the local bridge.

Timeouts and production guardrails

Timeouts are operation-specific across Codex, the MCP BridgeClient, the local HTTP bridge and Qt's main-thread dispatcher:

The recommended Codex tool_timeout_sec is 210 seconds so the MCP client can receive the bridge's structured result. If a timed-out Qt operation is already running, operation_may_complete=true is preserved and later calls receive BRIDGE_BUSY until Krita actually finishes.

Keep allowed_roots as narrow as practical, keep ordinary versioned or manual KRA backups, and do not treat the bridge timeout as cancellation. The bridge is local-only and binds exactly to 127.0.0.1.

See Windows installation, tool behavior and limits, security, and the GitHub releases.

License

Released under the MIT License. Copyright (c) 2026 Nicklas Desens.