tvsub MCP

<!-- mcp-name: io.github.launzi/tvsub-mcp -->

tvsub-mcp is the MCP companion for tvsub, an experimental subtitle overlay for Apple TV.app on macOS. It lets an MCP client inspect the current playback item, choose or translate a subtitle file, adjust its appearance, start or stop the overlay, and calibrate subtitle timing.

Supported player: purchased and rented films in macOS Apple TV.app (Prime Video support is being explored and is not currently available). Subtitle formats: SRT, SMI/SAMI, VTT. Translation runs on your choice of three backends: an Anthropic API key, a signed-in Claude Code CLI (Claude subscription), or a signed-in Codex CLI (ChatGPT subscription) — subscription backends add no API charges.

The server does not download subtitles, bypass DRM, modify video, or launch TV.app. You provide subtitle files that you have the right to use and start playback yourself.

Two directions, one workflow

If a foreign, classic, or multilingual film you purchased in Apple TV.app does not include Korean—or another language you need—bring a lawfully obtained subtitle file, translate it with your Claude or ChatGPT subscription, and display it as an overlay. The same workflow works in the other direction: viewers worldwide can translate lawfully obtained subtitles for Korean films and series into their own language.

Apple TV.app에서 구매한 외화·고전·다국어 영화에 한국어 또는 원하는 언어 자막이 없다면, 정당하게 보유한 자막 파일을 불러와 Claude나 ChatGPT 구독으로 번역한 뒤 오버레이로 표시할 수 있습니다. 같은 방식으로 전 세계 시청자도 한국 영화와 시리즈의 정당하게 보유한 자막을 자신의 언어로 번역해 시청할 수 있습니다.

Requirements

• macOS
• tvsub, installed and built
• Python 3.12 or later
• uv for the recommended uvx installation
• For subtitle translation, one of: an Anthropic API key, a signed-in Claude Code CLI (Claude subscription), or a signed-in Codex CLI (ChatGPT subscription). No key or CLI is needed for any other tool

Install and register with Claude Code

Replace /absolute/path/to/tvsub with the directory containing tvsub's build/, config/, src/, and subtitles/ directories.

brew install uv

claude mcp add --transport stdio --scope user tvsub -- \
  uvx tvsub-mcp==0.2.1 \
  --tvsub-root /absolute/path/to/tvsub

claude mcp get tvsub
claude mcp list

Translation picks a backend automatically: an Anthropic API key if present, then a signed-in Claude Code CLI, then a signed-in Codex CLI. Set TVSUB_TRANSLATE_BACKEND (auto, api, claude, codex) or the backend tool argument to override. With a subscription CLI signed in you can skip the key entirely. To use the API backend, export your key and include it when registering the server — or store it once in macOS Keychain (service kim.youngji.tvsub.anthropic), which the server also reads.

export ANTHROPIC_API_KEY="your-key"

claude mcp add --transport stdio --scope user \
  --env ANTHROPIC_API_KEY="$ANTHROPIC_API_KEY" \
  tvsub -- uvx tvsub-mcp==0.2.1 \
  --tvsub-root /absolute/path/to/tvsub

Other stdio MCP clients can launch the same command:

uvx tvsub-mcp==0.2.1 --tvsub-root /absolute/path/to/tvsub

Tools

Tool	Purpose
now_playing	Read the current Apple TV.app title, content ID, position, and playback state.
list_subtitles	List and parse SRT, SMI, SAMI, and VTT files in tvsub's subtitle library.
load_subtitle	Select a subtitle file for the current content while preserving sync anchors by default.
translate_subtitle	Estimate or perform an LLM translation with cue and timecode validation. Supports backend selection, glossary injection, and partial retranslation by line or time range.
set_glossary	Create or update a per-title glossary (names, honorifics, relationships, forbidden translations) that is injected into translation prompts.
mark_reviewed	Promote a translated subtitle's provenance from ai_draft to user_reviewed.
list_fonts	List installed macOS fonts and check sample glyph coverage.
set_style	Change font, size, colors, outline, background, and screen position.
start_overlay	Start tvsub with the selected subtitle and style.
stop_overlay	Stop only the overlay process started by this server.
calibrate_sync	Store one or more dialogue anchors and calculate timing offset and drift.
status	Summarize playback, overlay, subtitle, style, and calibration state.

Before translating, call translate_subtitle with dry_run=true to review the cue count, batch count, and estimated cost. Subscription backends report $0 (included in subscription). Every translation writes a .provenance.json sidecar recording backend, hashes, and review status.

Important notices

• Experimental software: expect rough edges and breaking changes. Keep a backup of your tvsub configuration and subtitle files.
• Data sent to Anthropic: translation sends the selected subtitle text and surrounding subtitle context to the Anthropic API. Loading, styling, sync, and overlay controls do not send subtitle text to Anthropic.
• User-paid API usage: the api backend uses your Anthropic API key and all charges are your responsibility; estimates can differ from the final bill. The claude and codex backends run through your own signed-in subscription CLIs and add no API charges.
• Private API risk: tvsub reads Apple playback state through undocumented macOS MediaRemote interfaces. Apple does not support this integration and a macOS update may change or disable it.
• Content rights: you are responsible for having the right to process and translate subtitle files. Do not redistribute protected content without permission.
• This project is independent from and not affiliated with Apple or Anthropic.

Development

python3.12 -m venv .venv
.venv/bin/python -m pip install -e .
.venv/bin/python -m unittest discover -s tests -p 'test_*.py' -v
TVSUB_TEST_PYTHON="$PWD/.venv/bin/python" .venv/bin/python tests/stdio_smoke.py
bash scripts/hygiene-check.sh

Before tagging a release, run bash scripts/preflight.sh from the repository root.

Linux can run the unit tests and mock stdio smoke test. Apple TV.app, MediaRemote, CoreText, and the real overlay require macOS.

License

MIT. See LICENSE.