Connect Claude or ChatGPT to YouTube: upload videos and Shorts through MCP

What YouTube account do I need?

A Google account with a YouTube channel. Uploads count against the channel's daily API quota. Hub connects the channel through Google’s own sign-in, so the person who manages the channel completes that step.

1. Open Accounts in Hub and choose YouTube, or ask the assistant to call connect_channel with platform set to youtube. That tool only returns a link and an instruction for a person. It needs the channels:connect permission, which Hub’s consent screen ticks whenever the assistant asks for it.
2. Open the link and sign in to Google yourself.
3. Tell the assistant you are done. It calls list_channels with refresh: true and uses the returned channel ID, which begins with spc_. A channel name or handle is not a substitute for that ID.

Custom covers depend on the channel’s eligibility on YouTube; see YouTube’s thumbnail requirements. A cover never replaces the video: it is attached to the video item.

Connect Claude, ChatGPT, Cursor or another MCP client

Every client uses the same server URL, https://www.mellow.world/mcp. Menus change between client versions, so the official guides linked below describe the current screens. The last column says only what Mellow itself has tested.

1. Add the server in your client and select Connect. Sign in to Mellow if asked. Hub’s consent screen names the app that is asking.
2. Choose the permissions the task needs (below), select your YouTube channel, choose review or autopilot, a daily ceiling and an expiry, then approve.
3. Back in the client, run the read-only check from the prompts below. Confirm the profile, the mode and the YouTube channel ID. Agents shows the grant’s permissions, channels and expiry, which a client’s summary may leave out.
4. If a client cannot complete OAuth, create a key in Agents and set it as the client’s Authorization: Bearer header, from its secret settings or an environment variable. Never paste a key into a chat.

Which permissions to approve

The consent screen arrives with every permission the assistant asked for already ticked, except spending AI credits. Untick anything it should not have; otherwise one tap on Allow is enough.

What you delegate, and how to take it back

Hub treats an assistant’s access as a delegation you give once, with limits. On the OAuth consent screen you choose the permissions, the channels (the ones you select, or explicitly all), review or autopilot, a daily ceiling of 1 to 1,000 posts (50 by default) and an expiry of 1, 7 or 30 days (30 by default). Autopilot is the default: the assistant publishes on its own within those limits. Choose review and each post waits for you. A key or a connected app cannot approve its own post.

An API key is created by you, signed in, in Agents. It belongs to one profile and carries its own mode and daily limit; through the REST key route it can also be limited to channels and given an expiry. A key cannot create another key. Hub records the posts an assistant creates or has refused, approvals, reschedules, cancellations and connection attempts in a journal you read in Agents. Revoking a key or a connected app takes effect on its next request. Publishing always needs an idempotency key, so a retried request cannot publish twice.

YouTube rules Hub checks before anything is sent

This table is generated from the registry that validate_post enforces, the same one behind the rules for every network. These are Hub’s input rules. YouTube still judges the file itself: Hub does not download the video, so duration, size, aspect ratio and processing are YouTube’s to decide.

Shorts and horizontal videos

Exactly one video, including landscape. YouTube classifies eligible square or vertical videos up to three minutes as Shorts; there is no separate Shorts endpoint. Hub has no Shorts setting either. The classification is YouTube’s, under its current Shorts rules, and a 16:9 video stays a regular video. Mellow’s live test used a horizontal video, so how YouTube classifies a vertical upload made through Hub has not been observed yet.

Other YouTube fields are passed on when you set them in options.youtube, among them description, privacyStatus (public, private or unlisted), madeForKids and tags. A field you leave out is not sent, so the publishing provider’s or YouTube’s default applies. Set privacyStatus yourself rather than relying on a default.

Hub recognizes a video by the file extension in its URL. A URL without one is not type-checked, and YouTube decides when it fetches the file.

When validate_post refuses the post

Read ok, issues and notes in the result. The check publishes nothing and reports every problem at once, each with its field and, for a network rule, its channel. Fix them together and validate again.

Other refusals concern the request or the grant: schedule_in_past (use a future time with a UTC offset), insufficient_scope (approve a delegation with the missing permission), channel_out_of_scope (the channel is not in the grant), and at creation daily_limit_reached and idempotency_key_reused. A passing check is not proof of publication: YouTube can still refuse the file or the account. The free post checker runs the same input rules on a draft before you connect anything.

Prompts you can paste

Replace the bracketed parts. Each prompt names the tools to call, so the assistant does not have to guess the order.

Check the connection, read-only

Use only Mellow Hub. Call whoami, then list_channels, then list_platforms.
Tell me my YouTube channel ID, whether this connection is in review or
autopilot mode, how many posts it may still create today, and YouTube's
rules. Do not upload, create, schedule or publish anything.

Validate a Short, then schedule it for 18:00

Use Mellow Hub. List my YouTube channel and validate this Short before
scheduling it for 18:00 on [date] in [your timezone].
Video: [public https URL ending in .mp4, vertical, up to three minutes]
Title: [title]
Caption (becomes the description): [text]

1. Call register_media on the video URL.
2. Call validate_post for my YouTube channel with options.youtube.title,
   options.youtube.privacyStatus "public" and scheduledAt written with an
   explicit UTC offset. Fix every issue it reports, then validate again.
3. When ok is true, call create_post once with idempotencyKey
   "yt-short-[date]-1800". If it times out, retry with the same key.
4. Call get_post and report the YouTube target's status and link.

A horizontal video, private first, with your own cover

Use Mellow Hub. Publish my horizontal video to my YouTube channel as a
private video first, with a custom cover.
Video: [public https URL of the .mp4]
Cover: [public https URL of a 16:9 JPEG]
Title: [title]

Put the cover in thumbnailUrl on the video's media item; do not add it as
a second media item. Set options.youtube.privacyStatus to "private".
Validate first and fix every issue. Then call create_post once with
idempotencyKey "yt-[short-name]-private-1". Call get_post until the
YouTube target is published or failed, and report the link or the error.

For a file on your computer, an agent that can make HTTP requests, such as Claude Code or a script of your own, can call request_upload_url, send the bytes with PUT to the returned uploadUrl and use the returned mediaUrl. An assistant that only has Hub’s tools cannot send file bytes itself, so give it a public https URL. Keep that URL reachable until YouTube has the video.

To make the cover, see thumbnails over MCP below and the AI YouTube thumbnail generator. Generating a cover through MCP spends AI credits and needs the separate ai:generate permission, which is not part of the default request.

Thumbnails, banners and avatars over MCP

Since October 24, 2026 the same server makes the picture as well as the post. Creative Studio’s thumbnail engine — the one behind Mellow’s AI YouTube thumbnail generator — is a set of tools an agent calls. The ones that draw spend credits and need the ai:generate and posts:write permissions, a maxCredits cap and an idempotencyKey; a key or app approved since then also carries a daily credit ceiling you choose, and is refused with daily_credit_limit past it. None of them publishes or buys credits.

A made picture is a Studio project: poll studio_job, take the file with studio_export and put it in thumbnailUrl on the video item of create_post. Banners and avatars are export only: the person uploads them in YouTube Studio. A prompt that goes from idea to a prepared post, and stops before publishing:

Use Mellow Hub. Make a thumbnail for my video about [topic].
Call studio_thumbnail_ideas and show me the ideas. For the one I pick,
call studio_quote, then studio_thumbnail with format "16:9", variants 2,
the headline in quotation marks, maxCredits from the quote and a stable
idempotencyKey. Poll studio_job, run studio_thumbnail_review on each
version and tell me the strengths and fixes. Do not improve, export or
publish anything until I say which version to use.

Without an agent, the same review runs free on the YouTube thumbnail tester. The whole package — title, description, channel art — is in YouTube packaging.

Publish once, then read the YouTube result

create_post is the step that publishes or schedules. It needs an idempotencyKey of 8 to 120 letters, digits or the characters . _ : -, stable for this post, such as yt-short-2026-10-02-1800. If the response is lost or times out, send the same request with the same key: Hub returns the original post instead of making a second one. Reusing a key for different content is refused.

Under a review-mode grant the post comes back as pending_review and waits until you approve it, signed in, in Hub’s Posts or Queue screen. Under autopilot it goes out at scheduledAt, or immediately without it. Always write scheduledAt with Z or an explicit UTC offset.

Then call get_post and read the YouTube entry in targets, not only the post’s status. publishing means YouTube has not reported a result yet; published comes with the video link; failed comes with the network’s message. A post sent to several networks can end partial. Hub sends a refused channel again by itself where that can help, and waits out YouTube’s daily upload limit; while it does, the target reads scheduled with waiting. For one that still reads failed, call retry_post: it sends the same post to the failed channel alone, so nothing that went out is duplicated. Once YouTube has published a video, Hub cannot edit or remove it; cancel_post works only before it goes out.

Each destination counts once against your plan’s monthly publications. Validating, drafting and connecting work without a plan; publishing needs an active one. See plans.

What Mellow has tested with YouTube

On September 21, 2026, Mellow’s own test of the MCP workflow on the production service uploaded a 1280×720 test video, validated the post and published it to a YouTube channel as a private video, with a cover generated in Creative Studio attached as its thumbnail. The YouTube destination reached published.

That test does not cover everything on this page. Not tested yet: a vertical upload that YouTube classifies as a Short, a public or unlisted video, and granting a YouTube channel through ChatGPT’s or claude.ai’s own connector screens. Claude’s web connector completed Hub’s consent once, on September 9, 2026, with read-only access to an Instagram channel. Cursor has not been tested.

Questions

Related

• Publish to social media with an MCP server: the workflow for every network.
• Threads MCP guide and Instagram MCP guide.
• The same for TikTok, LinkedIn, Facebook, X, Pinterest and Bluesky.
• Publish a YouTube video with its thumbnail, and the AI YouTube thumbnail generator.
• YouTube packaging: thumbnail, title, description, banner and avatar.
• API and MCP reference and rules for every network.
• Plans: each destination counts once against the monthly publications.