youtube-mcp

An MCP server for authenticated YouTube writes — uploading videos, attaching real caption tracks, managing playlists, editing metadata.

It is a thin, guarded bridge over a working yt_write.py CLI rather than a reimplementation of one, and most of what is interesting here is the guards. Each exists because the obvious implementation fails in a way that produces no error at all.

The failure this server exists to prevent

YouTube channels frequently live under Brand Accounts. At the OAuth consent screen, Google lists brand accounts as peers of your email address, not underneath it — so the row bearing your own name is your personal channel, which usually owns nothing.

Pick that row by mistake and everything still works. The token is valid. Every API call returns HTTP 200. Uploads succeed. They just land on the wrong channel, and you find out days later.

So assert_safe_channel runs before every write, not once at startup — a token can be replaced underneath a running process. It costs 1 quota unit to protect a 1,600-unit upload.

youtube_auth_status()
→ { ok: true, channels: [{ title: "…", allowed: true }], quota: {…} }

Call it first in any session that will write.

Uploads are asynchronous, and that is not a style choice

A 134 MB file takes minutes at 8 MB chunks; hour-long recordings run past 400 MB. A synchronous tool call reports a timeout while the transfer is still running — and the natural response, retrying, burns a second 1,600 quota units against a 10,000/day cap.

job = youtube_upload_video(file="/abs/path.mp4", title="…")
      → { job_id: "a1b2c3", status: "queued" }

youtube_upload_status(job_id="a1b2c3")
      → { status: "uploading", progress: 45 }
      → { status: "done", verified: true, url: "https://youtu.be/…" }

verified: true appears only after a read-back confirms the video exists and is owned by this token. If you are closing a task or a checklist row on the strength of an upload, gate it on verified, not on an id coming back from the insert call.

Jobs are in-memory and do not survive a restart. If you lose one, check the channel before re-uploading.

Quota is the real ceiling

Against a default 10,000/day project quota, that is 4–5 uploads per day. A backfill of any size is a multi-day plan, not an afternoon.

The ledger resets at midnight US Pacific and refuses an upload before spending when the day is gone — a videos.insert that dies mid-transfer still costs the full 1,600, and so does the retry. It counts only what this server spent, so treat it as a floor: usage from the CLI or another client is invisible to it.

Enforced locally, not left to the API

• privacy defaults to private. Never public by default. Schedule with publish_at instead of publishing straight out.

• publish_at requires privacy=private. YouTube rejects it otherwise; caught locally so you get a sentence instead of an opaque 400.

• Maximum 15 tags. The 16th is refused, never silently trimmed — a quietly dropped tag is worse than an error.

What it deliberately does not do

End screens and info cards. They are not in the YouTube Data API at all — Studio-only, permanently. Any tool claiming to set them would be lying, so there isn't one. youtube_upload_status returns a still_manual reminder instead.

Tools

Install

Requires Python 3.11+, uv, and a yt_write.py CLI exposing _service(), _resumable() and channel constants.

uv sync

Add to .mcp.json:

{
  "mcpServers": {
    "youtube": {
      "type": "stdio",
      "command": "uv",
      "args": ["run", "--directory", "/path/to/youtube-mcp", "python", "-m", "youtube_mcp"],
      "env": {
        "YT_WRITE_PATH": "/path/to/yt_write.py"
      }
    }
  }
}

Configuration

YT_WRITE_PATH has no default on purpose. A default path for the one file this server bridges would be a silent fallback over an endpoint — the class of bug that hides a misconfiguration until it matters.

If your setup keeps two copies of yt_write.py at different paths, set YT_WRITE_MIRROR_PATH. They are separate inodes, so editing one and not the other is a live trap; youtube_auth_status sha-compares them and reports drift rather than picking one silently.

At least one allowed channel must resolve, or the server refuses to start — without an allowlist it cannot distinguish a correct upload target from a silently wrong one, which is the whole point.

Auth

Credentials live wherever the wrapped yt_write.py puts them (CONFIG_DIR), typically client_secret.json + token.json at chmod 600. Scopes: youtube, youtube.force-ssl, youtube.upload.

auth cannot run from a tool call. It opens a browser and blocks on a localhost callback, which would hang the MCP client with no way out. When the token is missing, tools return an actionable error naming the command a human should run:

python /path/to/yt_write.py auth

At the chooser, pick the Brand Account row — never the personal row bearing your own name.

Two related traps worth knowing: Brand Accounts are not members of a Workspace org, so an Internal OAuth app returns Error 403: org_internal — the app must be External. And it must be published to Production; Testing mode expires refresh tokens every 7 days.

Implementation note: stdout is the transport

MCP stdio servers speak JSON-RPC on stdout. The wrapped CLI prints constantly — progress lines, banners, reminders — so one stray print corrupts the stream and the client drops the connection. Every call into that module runs inside a redirect_stdout buffer, surfaced as cli_output where it is useful.

If you fork this to wrap a different CLI, that is the part to keep.

License

MIT