CutSmith

Workflow-level MCP server for Final Cut Pro. Lets any MCP-capable LLM (Claude, Hermes, Cursor, …) assemble rough cuts, clean up edit artifacts, distribute captions, and QC timelines — on stock Final Cut Pro, no patched builds or kernel injection.

The idea is not "another wrapper around FCP menus" (see Prior art). The primitive tools already exist; CutSmith sits a level above: it does the workflows that turn raw recordings into a finished timeline, built directly on Apple's FCPXML interchange format and ffmpeg audio analysis.

Phase 1 focuses on the four pain points podcast/video editors complain about most: per-source sync drift, invisible loudness decisions, glitch frames left by silence removal, and captioning. Each maps to a tool below.

Tools (9)

All tools page or cap their output, so hour-long episodes analyze without flooding model context. Every generated file in the test suite validates against Apple's official FCPXML v1.11 DTD.

Related MCP server: fcp-mcp-server

The sync-offset fix

Riverside/podcast recordings drift per guest. Instead of manually nudging clips every session, CutSmith turns the fix into data: each asset carries a syncOffsetSecs, and assemble_rough_cut applies it mathematically to every in-point. Set it once per guest.

Why not inject into FCP?

Bottom line: splice-in works in other tools; here it is out of scope. CutSmith only reads and writes documented, forward-compatible formats (FCPXML 1.11) plus AppleScript that Apple ships. It cannot break your libraries or get your FCP version bricked by an macOS update — a real consideration for production machines.

Install

Requirements: macOS, Node 18+, Final Cut Pro 10.6+ (only for the FCP roundtrip tools; analysis/assembly work without it), ffmpeg on PATH (audio tools).

git clone https://github.com/msfbeast/cutsmith.git
cd cutsmith
npm install && npm run build
npm test && npm run smoke   # 20 unit tests + 8 end-to-end checks

Claude Desktop

~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "cutsmith": {
      "command": "node",
      "args": ["/absolute/path/to/cutsmith/dist/index.js"]
    }
  }
}

Claude Code

claude mcp add cutsmith -- node /absolute/path/to/cutsmith/dist/index.js

Hermes Agent (~/.hermes/config.yaml)

mcp_servers:
  cutsmith:
    command: "node"
    args: ["/absolute/path/to/cutsmith/dist/index.js"]

Example flow

You:    "Here are yesterday's Riverside files for Ep 43. Build a rough cut."
LLM:    analyze_silence on each guest track
        → assemble_rough_cut with keptRegions you approve, syncOffset for the
          cohost, targetLufs -16 with normalize: true
        → import_xml_into_fcp
        → detect_glitches on the import, fix, re-import
You:    review the timeline in FCP, tweak, ship.

Roundtrip notes

FCP's AppleScript dictionary is limited. XML export timing varies by FCP version — export_project_xml does its best via AppleScript and falls back with instructions (File > Export XML… → re-run analyze_timeline on the file). Import of generated XML is reliable: File > Import XML… or import_xml_into_fcp. Read FCPXML on Apple's docs for the format.

Prior art

• SpliceKit — the deepest FCP MCP (~200 tools via ObjC runtime, requires patched FCP build)

• fcp-mcp — 30 safe FCPXML/QC/roundtrip tools

CutSmith is the workflow layer: assemble-from-scratch, audio-measured gain, sync offsets, caption chunking — with tests that verify the actual written timelines.

Verifying on a FCP machine

The whole run is one command — every check that can only pass with Final Cut Pro present:

node test/acceptance.mjs

• exit 10 + install instructions → FCP missing/unusable (nothing else tested)

• PASS list + exit 0 → AppleScript roundtrip live, DTD-certified project imported into real FCP

The 90-day free FCP trial (Mac App Store) is enough; remove it after testing if you don't own it.

Manual depth-checks after a pass:

1. npm install && npm run build && npm test && npm run smoke — all 20 unit tests + 12 smoke checks must pass.

2. Launch FCP once by hand first (first-run dialogs out of the way); grant macOS Automation permission when the acceptance run asks.

3. In FCP, confirm the imported event ("Cutsmith Acceptance"): clips land, titles render, audio present.

4. validate_dtd on any FCP-exported XML — must pass both ways.

Known limitations (read before trusting it with a master timeline)

• Roundtripping complex timelines is lossy. The parser reads compound clips, attached audio sub-clips and effect payloads raw; the generator writes flat spines. Analyze-and-assemble-new is the safe path; in-place regeneration of an editor's intricate project will flatten structure (tools warn and refuse unless force=true).

• Captions ship as Basic Text titles (universal), not native <caption> elements; word timings in chunked captions are evenly distributed, not word-accurate.

• Volume ducking is stepped per region (FCPXML has no editable crossfade automation in 1.11); keep duck levels moderate.

• Drop-frame timecode (29.97 DF) and >2-channel audio layouts are not yet mapped.

• import_xml_into_fcp / export_project_xml behavior varies across FCP versions; validated import path is FCP's own File > Import XML. Apple's DTD ships inside FCP and cannot be redistributed here.

Credits

DTD verification uses Apple's FCPXML DTDs, discovered at runtime from your FCP install; the DTD forms matched against OpenFCPXMLKit's published copies during development.

License

MIT