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. Hermes reaches all of it through one connection. This page is about one slice of that — what Hermes can actually do on YouTube, and what YouTube will not let it do.
Connect Hermoso to Hermes
- 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 pointing at the hosted endpoint with your key:
{ "url": "https://app.hermoso.ai/mcp", "headers": { "Authorization": "Bearer <your key>" } } - Ask Hermes 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.
Hermoso is not affiliated with or endorsed by the makers of Hermes, and this is not a bespoke integration — it is the same generic HTTP MCP block any conforming client takes. We would rather say that than imply a partnership that does not exist.
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 Hermes 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 Hermes
Ask for it in ordinary language — these are sentences, not a DSL:
“Upload each finished film unlisted with a title under 100 characters, a full description with links, ten tags and a generated thumbnail.”
That walks make_thumbnail → post_to_youtube → set_youtube_thumbnail → youtube_video_insights. Approval behaviour is yours to configure. Hermoso’s own guarantees do not depend on it: campaigns are born paused, spend switches are confirm-gated, and no generation call runs without a verified account behind it.
Hermes on YouTube: the part that bites
Pass description and tags explicitly, every time. The caption becomes the title and is capped at 100 characters; the description is a separate 5,000-character field, and an upload that goes out with an empty one has lost the links and the CTA in a way nobody notices until much later.
For unattended runs the hermoso CLI with --json is easier to assert on than a tool manifest, and much cheaper in context.
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 Hermes 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 Hermes, post to: Facebook · Instagram · Threads · TikTok · X · LinkedIn · Pinterest — or see everything Hermes can publish to.
Post to YouTube from: Claude · ChatGPT · Claude Code · Cursor · Codex · Cline · OpenClaw
Frequently asked questions
Can Hermes 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 Hermes with an Authorization: Bearer header. Hermes 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 Hermes?
Two steps, once each. Create an API key in Hermoso under Settings → Agents & API keys, then add https://app.hermoso.ai/mcp to Hermes with an Authorization: Bearer header. Then connect YouTube inside Hermoso under Settings → Connectors, which is an OAuth consent screen in a browser. After that Hermes publishes to YouTube as an ordinary tool call.
Does Hermes need my YouTube password?
No. You connect YouTube to Hermoso once through an OAuth consent screen in a browser, and Hermes then reaches it as a tool call. Linking an account is the one step that is not headless; nothing after it needs a password, and no credential is ever handed to the model.
Can Hermes research YouTube before it posts?
Yes. search_youtube searches the public YouTube index, list_youtube_videos reads your own uploads including unlisted ones, and analyze_video returns a competitor film’s voiceover, on-screen text and beat list with timestamps.
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