Hermoso is a marketing MCP server: 301 tools over one OAuth’d endpoint that let an agent research the ads already running in a market, generate finished image and video ads, publish them, and build the paid campaigns behind them. Cline reaches all of it through one connection. This page is about one slice of that — what Cline can actually do on YouTube, and what YouTube will not let it do.
Connect Hermoso to Cline
- Create an API key. In Hermoso, open Settings → Agents & API keys and press ＋ Create API key. It looks like
hmk_…and carries real spend authority, so treat it like a password. - Add an MCP server in Cline’s MCP settings, pointing at the hosted endpoint with your key:
{ "url": "https://app.hermoso.ai/mcp", "headers": { "Authorization": "Bearer <your key>" } } - Ask Cline for something. “Pull my three closest competitors’ longest-running ads and remix the best hook into a 9:16 video,” or “post this render to the channel.” The agent picks the tools; you approve the spend.
This is Hermoso’s generic HTTP MCP block rather than a bespoke Cline integration, and it is worth saying so plainly. What is Cline-specific on our side is the authorization server: it accepts loopback (http://127.0.0.1:PORT/…) redirect URIs precisely so locally installed agents like Cline can complete a registration handshake at all.
Then connect YouTube itself, once, under Settings → Connectors in Hermoso. That is an OAuth consent screen, so it is the one step that needs a browser — everything after it is a tool call.
The YouTube tools Cline gets
post_to_youtube— uploads a finished video with a title, a description of up to 5,000 characters, up to 30 tags, and a privacy setting.schedule_post— queues the upload — with the description and tags carried through, which is not something to take for granted.set_youtube_thumbnail— puts a designed thumbnail on the upload. It is the single biggest lever on click-through, and YouTube otherwise picks a frame more or less at random.make_thumbnail— generates that thumbnail in the first place.update_youtube_video / list_youtube_videos— edit an upload’s metadata, or list your own uploads — including unlisted and private ones a public search cannot see.youtube_video_insights / youtube_channel— views, watch time, average view percentage and subscribers gained.list_youtube_comments / reply_to_youtube_comment— read and answer comments as the channel.
The unit really is a video: post_to_youtube takes a videoUrl and there is no image path at all. Two smaller gates worth knowing before an automated upload: a Google project that has not been verified has videos.insert locked to private regardless of what you ask for, and custom thumbnails need a phone-verified channel.
YouTube limits worth knowing before you automate anything
| Text | A YouTube title is capped at 100 characters — and a scheduled item’s text becomes the title. The description is a separate field of up to 5,000 characters, carrying up to 30 tags. It is enforced when the post is created or queued — refused while you are still there to fix it, rather than silently cut on the way out. |
|---|---|
| Visibility | Public, unlisted or private. There is no Studio draft — “YouTube’s API can upload as public, unlisted or private, but it cannot create a Studio draft”, so unlisted is the closest thing to a review state, and it is what an immediate post defaults to so an ad-ready upload is not accidentally public. |
| Carousel | Refused, by name. “YouTube’s unit is a video, not a set of stills. Turn the slides into a video (Hermoso can stitch them) and post that instead, or drop YouTube from this post.” That is not a limitation Hermoso invented to avoid work — it is what YouTube is — and the refusal comes at enqueue, with the way forward attached, rather than as a silently posted first slide. |
| Which account | None — YouTube publishes to the connected channel. |
Try it in Cline
Ask for it in ordinary language — these are sentences, not a DSL:
“Upload this demo video unlisted with a title under 100 characters, a full description with our docs link, ten tags, and a generated thumbnail.”
That walks make_thumbnail → post_to_youtube → set_youtube_thumbnail → youtube_video_insights. Cline asks before each tool call by default, which is the behaviour you want on anything that publishes.
Cline on YouTube: the part that bites
Unlisted is the safe default for an agent with auto-approve anywhere in its configuration, because an accidental public upload is not something you can quietly undo. It is also the honest one: YouTube's API cannot create a Studio draft, so unlisted is the only pre-publish state that exists.
If you run Cline in auto-approve, exclude the publishing and campaign tools — those are the ones with a public or a financial consequence.
Research YouTube before you post
search_youtube searches the public YouTube index — which is a different question from “what have I uploaded”, and list_youtube_videos is the tool for that one. For a competitor’s film, analyze_video returns the voiceover, the on-screen text and the beat list with timestamps, which is what you actually want before rebuilding a hook.
The paid half
Hermoso’s Google Ads tools build search, display and Performance Max campaigns — the whole tree in one atomic operation, read back from Google before your agent narrates it — plus Keyword Planner volumes, conversion actions, and sitelinks and callouts created and attached. There is no YouTube video-campaign builder, and it would be wrong to imply one; a YouTube video asset can be uploaded and attached, but the campaign types Hermoso creates are search, display and Performance Max.
What Cline cannot do on its own
An agent with a budget is only useful if the blast radius is bounded, so the fence is in the server rather than in a prompt. Every ad campaign, ad set, ad group and ad is created paused, and the status switches that arm real money refuse to run without an explicit confirmation flag. Every render is quoted first — hermoso_capabilities publishes each model’s exact credit cost before anything spends — and credits are reserved before the first provider call and settled at the exact cost afterwards, so a failed dispatch refunds rather than leaving you billed for nothing. Deletes are confirm-gated too, and every campaign tree is read back from the ad platform before your agent tells you what it built.
One step is deliberately not headless: linking an account is an OAuth consent screen, so you connect the channel once in a browser. Everything after that is a tool call.
The rest of the matrix
From Cline, post to: Facebook · Instagram · Threads · TikTok · X · LinkedIn · Pinterest — or see everything Cline can publish to.
Post to YouTube from: Claude · ChatGPT · Claude Code · Cursor · Codex · OpenClaw · Hermes
Frequently asked questions
Can Cline post to YouTube?
Yes, through Hermoso's MCP server. Create an API key in Hermoso under Settings → Agents & API keys, then add https://app.hermoso.ai/mcp to Cline with an Authorization: Bearer header. Cline then has 301 tools, including the ones that publish to YouTube — and the ones that research the ads already running in your market and render the creative in the first place.
How do I connect YouTube to Cline?
Two steps, once each. Create an API key in Hermoso under Settings → Agents & API keys, then add https://app.hermoso.ai/mcp to Cline with an Authorization: Bearer header. Then connect YouTube inside Hermoso under Settings → Connectors, which is an OAuth consent screen in a browser. After that Cline publishes to YouTube as an ordinary tool call.
Can Cline post a carousel to YouTube?
No, and the refusal says why rather than saying "unsupported": YouTube’s unit is a video, not a set of stills. Hermoso can stitch the slides into a video and post that instead. Cline calls the same publish tool either way, and a channel that cannot carry a carousel is refused with the real reason attached.
Can Cline run YouTube ads as well as posting?
Hermoso builds Google Ads search, display and Performance Max campaigns, with Keyword Planner volumes and conversion actions. There is no YouTube video-campaign builder, and we do not imply one.
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