clipwright 0.2.0

MCP server group wrapping FFmpeg/OTIO. Provides primitives to manipulate video editing workflows from AI agents.

Clipwright

For Japanese, see README.ja.md.

MCP server group wrapping FFmpeg/OTIO. Provides primitives to manipulate video editing workflows from AI agents.

Prerequisite: FFmpeg

Clipwright requires ffprobe (runtime) and ffmpeg (test fixture generation) on PATH. Binaries are not included.

Installation (Windows / WinGet)

winget install Gyan.FFmpeg

PATH takes effect after shell restart. When using with Claude Code, restart the app for PATH to become active.

If you cannot wait for a restart, specify environment variables directly:

# runtime: ffprobe only
export CLIPWRIGHT_FFPROBE="C:/Users/<user>/AppData/Local/Microsoft/WinGet/Packages/Gyan.FFmpeg_Microsoft.Winget.Source_8wekyb3d8bbwe/ffmpeg-8.1.1-full_build/bin/ffprobe.exe"

# test: both ffmpeg + ffprobe (for test fixture generation)
export CLIPWRIGHT_FFMPEG="C:/Users/<user>/AppData/Local/Microsoft/WinGet/Packages/Gyan.FFmpeg_Microsoft.Winget.Source_8wekyb3d8bbwe/ffmpeg-8.1.1-full_build/bin/ffmpeg.exe"

Environment Variable Usage

Variable	Purpose
CLIPWRIGHT_FFPROBE	Runtime only. Used by the clipwright_inspect_media tool
CLIPWRIGHT_FFMPEG	Test only. Used by the sample_media fixture in conftest.py

Runtime depends only on ffprobe. ffmpeg is used only for test fixture generation (design: [DC-AM-008]).

---

Development Environment Setup

# Install dependencies
uv sync --dev

# Run tests (with coverage)
uv run pytest --cov=clipwright --cov-report=term-missing

# lint / format
uv run ruff check src tests
uv run ruff format src tests

# Type checking
uv run mypy src

Integration Test Prerequisites

To run integration tests (tests that actually invoke ffprobe/ffmpeg), ffmpeg / ffprobe must exist on PATH or the following environment variables must be set:

# Specify path to ffprobe (used by runtime and integration tests)
export CLIPWRIGHT_FFPROBE="/path/to/ffprobe"

# Specify path to ffmpeg (used for test fixture generation)
export CLIPWRIGHT_FFMPEG="/path/to/ffmpeg"

If ffmpeg / ffprobe are already registered in PATH, setting environment variables is not required. If neither is found, integration tests are automatically skipped.

---

Development Notes: MCP Package

Adopted Package

Official MCP Python SDK (mcp[cli]) is adopted (ADR-5 confirmed).

mcp[cli]>=1.27.2

Importable via from mcp.server.fastmcp import FastMCP. Verified to work on Python 3.11 / Windows.

Annotation Syntax (Adopted Version)

from mcp.server.fastmcp import FastMCP
from mcp.types import ToolAnnotations

mcp = FastMCP("clipwright")

@mcp.tool(
    annotations=ToolAnnotations(
        readOnlyHint=True,
        destructiveHint=False,
        idempotentHint=True,
        openWorldHint=False,
    )
)
def clipwright_inspect_media(path: str) -> dict:
    """Probe a media file and return its information."""
    ...

ToolAnnotations fields: title, readOnlyHint, destructiveHint, idempotentHint, openWorldHint

outputSchema / structured_output

When mcp.tool(structured_output=True) is specified, Pydantic model return values are reflected in outputSchema as JSON Schema.

from pydantic import BaseModel

class MediaResult(BaseModel):
    ok: bool
    summary: str

@mcp.tool(structured_output=True)
def clipwright_inspect_media(path: str) -> MediaResult:
    ...

---

MCP Inspector Communication Procedure

How to manually verify the server using MCP Inspector (@modelcontextprotocol/inspector).

Setup (Node.js Required)

# Verify Node.js is installed
node --version
npx --version

Starting the Server and Connecting

# Start MCP Inspector and connect the server via stdio
npx @modelcontextprotocol/inspector uv run python -m clipwright.server

Browser opens automatically at http://localhost:5173 (or access manually).

The tool list (clipwright_init_project / clipwright_inspect_media / clipwright_read_timeline / clipwright_write_timeline) appears in Inspector, and you can manually execute each tool.

Expected Behavior

• 4 tools appear in the tool list
• Passing a non-existent path to clipwright_inspect_media returns an error envelope with ok=false
• If ffprobe is not set in PATH / environment variables, a DEPENDENCY_MISSING error is returned

---

Architecture Overview

src/clipwright/
  __init__.py       # Version definition
  schemas.py        # Shared Pydantic types (contract surface)
  envelope.py       # Return value envelope + error formatting
  errors.py         # Error codes + ClipwrightError exception
  process.py        # Subprocess runner (shell=False / timeout required)
  media.py          # ffprobe wrapper
  otio_utils.py     # OTIO helpers
  operations.py     # Declarative edit operation types + application logic
  project.py        # Project directory management
  server.py         # FastMCP server (4 tools exposed)

Dependency direction: schemas / envelope / errors (contract surface) → process / media / otio_utils / project → operations → server

For details, see docs/clipwright-spec.md.

---

MCP Client Registration

Each clipwright tool is a standalone MCP server. Register them in your MCP client configuration (.mcp.json / claude_desktop_config.json):

{
  "mcpServers": {
    "clipwright": {
      "command": "clipwright-mcp",
      "env": {
        "CLIPWRIGHT_FFMPEG": "/path/to/ffmpeg",
        "CLIPWRIGHT_FFPROBE": "/path/to/ffprobe"
      }
    },
    "clipwright-render": {
      "command": "clipwright-render",
      "env": {
        "CLIPWRIGHT_FFMPEG": "/path/to/ffmpeg"
      }
    }
  }
}

Set CLIPWRIGHT_FFMPEG and CLIPWRIGHT_FFPROBE environment variables if ffmpeg is not in PATH.

---

License

MIT — See LICENSE for details.