Hermoso is a marketing MCP server: 850+ 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. Gemini CLI reaches all of it through one connection. This page is about one slice of that — what Gemini CLI can actually do on YouTube, and what YouTube will not let it do.
Connect Hermoso to Gemini CLI
- Install the extension.
It installs the latest release of Hermoso’s public repository: five skills (research, ad-from-brand, generate, product-photoshoot and marketing) plus agemini extensions install https://github.com/hermoso-ai/hermosoGEMINI.mdcontext file. The skills run thehermosocommand throughnpx, so nothing is added to Gemini CLI’s tool list and nothing costs context until a command runs.gemini extensions listshows them under Agent skills. - Sign in once.
It opens a browser sign-in and stores an owner-only credential innpx -y hermoso auth login~/.hermoso/config.json. Gemini CLI can run it for you the first time it needs Hermoso. No browser on that machine? Create a key under MCP & CLI → Terminal & API keys and runnpx -y hermoso auth login --token hmk_…. - Optional: the MCP server as well.
Gemini CLI finds Hermoso’s authorization server when the first connection answers 401 and registers itself, so no key goes ingemini mcp add --scope user --transport http hermoso https://app.hermoso.ai/mcpsettings.json;/mcp auth hermosoinside a session runs the sign-in. The skills reach every tool without it. - Ask Gemini CLI 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.
We ran the install above on 2026-09-23 against Gemini CLI 0.60.0 in a clean home directory: it pulled the current release of hermoso-ai/hermoso, and gemini extensions list reported the five skills and the context file. The extension carries no MCP server of its own, which is deliberate: a tool list is loaded into every session, and skills cost nothing until they run. Hermoso is not affiliated with or endorsed by Google.
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 Gemini CLI 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 Gemini CLI
Ask for it in ordinary language — these are sentences, not a DSL:
“Upload ./renders/demo.mp4 to YouTube unlisted with a title under 100 characters, the description in ./docs/demo.md, ten tags and a generated thumbnail.”
That walks make_thumbnail → post_to_youtube → set_youtube_thumbnail → youtube_video_insights. Gemini CLI asks before it runs a shell command, and the skills act through the hermoso command, so a publish shows up as a line you can read before you say yes. For MCP tools it offers once, always for that tool, or always for the server.
Gemini CLI on YouTube: the part that bites
Pass the description as its own field. A scheduled item’s text becomes the 100-character title, and the 5,000-character description, which carries the links, stays empty unless you ask for it. Upload unlisted, since the API has no Studio draft, then flip it public with update_youtube_video once you have watched it. Custom thumbnails need a phone-verified channel.
Two Gemini CLI details decide how safe this is. gemini mcp add writes to the project’s .gemini/settings.json unless you pass --scope user, which is useful when one repo should always run against one brand. And never add Hermoso with --trust: it skips every confirmation for the server, including the ones in front of a publish. MCP tools arrive named mcp_hermoso_ plus the tool name, and --exclude-tools keeps any of them out entirely.
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 Gemini CLI 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 Gemini CLI, post to: Facebook · Instagram · Threads · TikTok · X · LinkedIn · Pinterest · Bluesky · Telegram — or see everything Gemini CLI can publish to.
Post to YouTube from: Claude · ChatGPT · Claude Code · Cursor · Codex · Cline · OpenClaw · Grok Bot · Hermes · Perplexity · Le Chat
Frequently asked questions
Can Gemini CLI post to YouTube?
Yes, with Hermoso's Gemini CLI extension. Run gemini extensions install https://github.com/hermoso-ai/hermoso, which adds five Hermoso skills that drive the hermoso command, then sign in once with npx -y hermoso auth login. The sign-in opens a browser and stores the credential itself, so there is no key to create and none to paste. If you also want Hermoso's tools in Gemini CLI's own list, gemini mcp add --scope user --transport http hermoso https://app.hermoso.ai/mcp adds the hosted server, which signs in with OAuth. Gemini CLI then has 850+ 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 Gemini CLI?
Two steps, once each. Run gemini extensions install https://github.com/hermoso-ai/hermoso, which adds five Hermoso skills that drive the hermoso command, then sign in once with npx -y hermoso auth login. The sign-in opens a browser and stores the credential itself, so there is no key to create and none to paste. If you also want Hermoso's tools in Gemini CLI's own list, gemini mcp add --scope user --transport http hermoso https://app.hermoso.ai/mcp adds the hosted server, which signs in with OAuth. Then connect YouTube inside Hermoso under Settings → Connectors, which is an OAuth consent screen in a browser. After that Gemini CLI publishes to YouTube as an ordinary tool call.
Can Gemini CLI 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. Gemini CLI calls the same publish tool either way, and a channel that cannot carry a carousel is refused with the real reason attached.
Can Gemini CLI 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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