Hermoso is a marketing MCP server: 876+ 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. Claude Cowork reaches all of it through one connection. This page covers one slice of that: what Claude Cowork can actually do on YouTube, and what YouTube will not let it do.
Connect Hermoso to Claude Cowork
- Copy the connector URL.
https://app.hermoso.ai/mcp - Claude → Customize → Connectors → ＋ Add → Add custom connector. Name it Hermoso and paste the URL. Leave the sign-in option on Claude’s default: Hermoso accepts Claude’s published client identity and also registers clients automatically, so there is no client ID to create.
- Connect and approve. Sign in with your Hermoso account on the consent page. No key is pasted.
- Open Cowork and hand it the job. Cowork sees the same connector. Ask it to list your connected channels first, so you know which accounts it can reach.
- Ask Cowork 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.
Anthropic’s help center lists custom connectors on Claude, Cowork and Claude Desktop, and Cowork itself on the paid plans: Pro, Max, Team and Enterprise. On Team and Enterprise an Owner adds Hermoso once under Organization settings, Connectors, and members press Connect. One detail decides the route: a local server in claude_desktop_config.json is not available in Cowork, so the hosted connector is the way in, not npx hermoso mcp. Read from Anthropic’s help center on 2026-10-03. Hermoso is not affiliated with or endorsed by Anthropic.
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 Claude Cowork 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, and carries the description and tags through with it.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, so an overlong post is refused while you are still there to fix it instead of being 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.” Hermoso did not invent that limit to avoid work; it is simply what YouTube is. The refusal comes at enqueue, with the way forward attached, instead of a silently posted first slide. |
| Which account | None. YouTube publishes to the connected channel. |
Try it in Claude Cowork
Ask for it in ordinary language. These are plain sentences, not a DSL:
“Upload our new explainer to YouTube unlisted with a title under 100 characters, a full description, ten tags and a generated thumbnail, then send me the link.”
That walks make_thumbnail → post_to_youtube → set_youtube_thumbnail → youtube_video_insights. How often Cowork stops to check with you is Cowork’s behaviour, not ours. Hermoso’s gates hold either way: campaigns are born paused, and spend switches and deletes need an explicit confirmation.
Claude Cowork on YouTube: the part that bites
Unlisted is the review state, because YouTube’s API has no Studio draft, so it suits a task that runs to the end on its own: you watch it, then make it public with update_youtube_video. Ask for the description explicitly. Otherwise the text becomes the 100-character title, and links belong in the description’s 5,000 characters.
Cowork can run shell commands, but Anthropic’s default network setting for that sandbox allows package registries rather than every domain, so the hermoso command line is not something to rely on there. The connector is unaffected: Anthropic says connector traffic keeps working whatever the sandbox’s network setting is.
Research YouTube before you post
search_youtube searches the public YouTube index. That 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 Claude Cowork 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). 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 Claude Cowork, post to: Facebook · Instagram · Threads · TikTok · X · LinkedIn · Pinterest · Bluesky · Telegram. Or see everything Claude Cowork can publish to.
Post to YouTube from: Claude · ChatGPT · Claude Code · Cursor · Codex · Cline · OpenClaw · Grok Bot · Hermes · Gemini CLI · Perplexity · Le Chat · Perplexity Computer · Paperclip · AI marketing in Claude
Frequently asked questions
Can Claude Cowork post to YouTube?
Yes, through the Hermoso connector you add in Claude. In Claude, open Customize, Connectors, add a custom connector with https://app.hermoso.ai/mcp and approve it with your Hermoso account. Cowork uses the same connector, and there is no key to paste. Claude Cowork then has 876+ tools, including the ones that publish to YouTube, plus 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 Claude Cowork?
Two steps, once each. In Claude, open Customize, Connectors, add a custom connector with https://app.hermoso.ai/mcp and approve it with your Hermoso account. Cowork uses the same connector, and there is no key to paste. Then connect YouTube inside Hermoso under Settings → Connectors, which is an OAuth consent screen in a browser. After that Claude Cowork publishes to YouTube as an ordinary tool call.
What is the YouTube caption limit when posting from Claude Cowork?
A YouTube title is capped at 100 characters. The description is a separate field of up to 5,000 characters, with up to 30 tags. A scheduled item’s text becomes the title, so both must be passed explicitly. Hermoso enforces it when the post is created or queued, so Claude Cowork is told immediately rather than failing later when nobody is watching.
Can Claude Cowork schedule a YouTube post for later?
Yes. schedule_post queues it on one calendar shared with every other channel, with a per-channel caption if the copy should differ, and list_scheduled and cancel_scheduled read and pull it back. YouTube is one of the ten channels that queue.
Can Claude Cowork post privately or as a draft to YouTube?
Yes: public, unlisted or private. There is no Studio draft in YouTube’s API, so unlisted is the review state, and an immediate post defaults to it. Hermoso refuses a visibility YouTube cannot honour at the moment you ask for it, rather than quietly publishing something weaker.
What does it cost to post to YouTube from Claude Cowork?
Publishing to YouTube costs no credits; YouTube charges nothing per API call. Credits are spent generating the video and the thumbnail. Plans are $19, $49 and $149 a month for 1,000, 3,000 and 10,000 credits, and every feature is on every plan including Free. The only exception is enterprise SSO.
Start free with 30 credits at signup and 250+ more to earn. Every feature is on every plan. Credits are spent only on AI models and Ad Spy research; posting, scheduling, ads management and analytics are free.
Start free → See pricing