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. Le Chat reaches all of it through one connection. This page is about one slice of that — what Le Chat can actually do on X, and what X will not let it do.
Connect Hermoso to Le Chat
- Copy the connector URL.
https://app.hermoso.ai/mcp - Le Chat → Intelligence → Connectors → + Add Connector → Custom MCP Connector. Name it Hermoso and paste the URL.
- Press Connect and approve. Le Chat detects Hermoso’s OAuth sign-in with dynamic client registration and opens the consent page. Sign in with your Hermoso account; there is no key to paste.
- Ask Le Chat 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.
Adding a custom connector is an admin action in Le Chat. On the Free, Pro and Student plans the account owner is the admin, so you can add Hermoso yourself, free plan included; on a team plan an admin adds it. The steps are quoted from Mistral’s MCP connector documentation, read on 2026-09-23. Hermoso is not affiliated with or endorsed by Mistral AI.
Then connect X 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 X tools Le Chat gets
post_to_x— posts text, an image or a video with alt text, a whole thread, a reply, a quote post, or a poll — and can restrict who is allowed to reply.post_x_article— publishes a long-form Article. Write it in Markdown and the headings, lists, quotes, links, code blocks and tables all carry across.edit_x_post— rewrites a post you have already published, inside the hour X allows.schedule_post— queues it on the shared calendar.x_post_metrics— the public counts on a post.x_post_insights— advertiser-grade numbers — impressions, link clicks, profile visits, video views and completion quartiles — for the last 28 hours only.x_post_insights_historical— the same numbers over any date range, up to 25 posts at a time. This is the one for “how did last month go”.x_mentions— who is talking about the brand.delete_x_post— removes a post.
X is the only connector that costs money per call, and the numbers are published rather than hidden. Meta, TikTok, LinkedIn, YouTube, Threads and Drive cost nothing per request; X charges us, so those calls bill a small number of credits each. A plain post is priced at $0.015 per request and a post containing a link at $0.200 — roughly 13× more. Deletes, reads and the alt-text metadata write each carry their own price, and insights bill per post returned. Link detection deliberately errs toward assuming a link is present, because guessing wrong the other way costs us 13×. The practical consequence: on X, one good post beats five, and your agent is quoted the price before it posts. Length is the posting account’s, not a flat 280. Hermoso reads the account’s own X subscription and sends up to 25,000 characters where Premium allows it, so a long post goes out whole rather than coming back refused, and nothing is ever truncated. That happens to be the cheap shape too: one long post is a single billed X call where the same words split across five posts are five. X Premium also unlocks two things Hermoso publishes for you: a long-form Article, written in Markdown with its headings, lists, quotes, code blocks and tables intact, and an edit to a post you have already published, inside the hour X allows.
X limits worth knowing before you automate anything
| Text | Length is the posting account’s: 280 characters ordinarily, up to 25,000 with X Premium. Hermoso reads the subscription from X, so a long post goes out whole. Nothing is ever truncated. 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 only. A post on X is public the moment it exists — there is no draft and no unlisted post in the API. Protected accounts exist, but that is an account-wide setting Hermoso neither reads nor controls, not a per-post choice. |
| Carousel | Refused, by name, and for a reason that is specific rather than generic: “X has no swipeable carousel. Its API attaches up to 4 media to a post and they render as a GRID — every image visible at once, nothing to swipe to — so a numbered ‘1/6 · SWIPE’ slide deck cannot be published there as intended. Post the single strongest slide to X, or drop X from this post.” A deck that instructs the reader to swipe, published as a grid, is worse than not publishing it. |
| Which account | None — X publishes to the connected account. |
Try it in Le Chat
Ask for it in ordinary language — these are sentences, not a DSL:
“Write one X post under 280 characters about the release, with the link, and tell me what it costs before posting.”
That walks get_brand → generate_text → post_to_x → x_post_insights_historical. Le Chat lets you set each connector function to Always allow or leave it asking. Mistral’s own advice is to pre-authorise read functions and keep write functions on manual approval, and that is the right split here: research and list tools can run freely, anything that publishes, schedules or deletes should ask.
Le Chat on X: the part that bites
Do not set post_to_x to Always allow in Le Chat. Every call it makes is a billed X request, and a pre-authorised tool never shows you the quote. Reads like x_post_metrics bill too, since X charges per request whatever the verb. Length follows the account’s subscription, and over-long text is refused, never cut.
Le Chat’s custom connectors do not pick up new tools after you connect; the list is what it loaded at that moment. Hermoso starts a connector on a short list and includes find_tools and call_tool, which reach every other tool by name, so a tool missing from the loaded list is still one request away.
Research X before you post
There is no X ad library to search. X research here is your own account: mentions, post metrics and the historical advertiser numbers. Everything else in the research surface — Meta, Google and LinkedIn ad libraries, organic TikTok, Instagram, YouTube, Reddit and Threads — is unaffected.
The paid half
X Ads landed in August 2026, so X is now both halves. The X Ads API is a separate product on a separate host with its own OAuth 1.0a signing, which is why it arrived after the rest — and Hermoso now builds the whole promoted-post tree on it: campaign, line item (X’s name for an ad group), promoted tweet, targeting, budgets, status and reporting. An X ad promotes a post, so the creative is a post — the same one Hermoso publishes organically. The switch that arms real money refuses to run without an explicit confirmation, exactly as on the other ten platforms. One thing to know before you plan a budget: X grants Ads API access per ad account rather than per app, so there is no OAuth button for it: you add Hermoso’s X user to your ad account at business.x.com → Account access, and it appears in list_x_ads_accounts with the permission level X gave it.
What Le Chat 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 Le Chat, post to: Facebook · Instagram · Threads · TikTok · YouTube · LinkedIn · Pinterest · Bluesky · Telegram — or see everything Le Chat can publish to.
Post to X from: Claude · ChatGPT · Claude Code · Cursor · Codex · Cline · OpenClaw · Grok Bot · Hermes · Gemini CLI · Perplexity
Frequently asked questions
Can Le Chat post to X?
Yes, through Hermoso's MCP server. In Le Chat, add https://app.hermoso.ai/mcp as a custom connector and approve it with your Hermoso account — there is no key to paste. Le Chat then has 850+ tools, including the ones that publish to X — and the ones that research the ads already running in your market and render the creative in the first place.
How do I connect X to Le Chat?
Two steps, once each. In Le Chat, add https://app.hermoso.ai/mcp as a custom connector and approve it with your Hermoso account — there is no key to paste. Then connect X inside Hermoso under Settings → Connectors, which is an OAuth consent screen in a browser. After that Le Chat publishes to X as an ordinary tool call.
What is the X caption limit when posting from Le Chat?
That depends on the account, and Hermoso checks rather than guessing. An ordinary X account is capped at 280 characters; one with X Premium goes up to 25,000. Hermoso reads the subscription from X and sends the post, so a long post goes out whole, and nothing is ever truncated. On a Premium account one long post usually reads better than a thread and costs less, because it is a single billed X call where five parts are five. Premium also unlocks long-form Articles, written in Markdown, and an edit to a post already published inside the hour X allows. Hermoso enforces it when the post is created or queued, so Le Chat is told immediately rather than failing later when nobody is watching.
Can Le Chat run X ads as well as posting?
Yes, since August 2026. X Ads runs on a separate host with its own OAuth 1.0a signing, and Hermoso builds the whole tree on it — campaign, line item, promoted tweet, targeting, budgets, status and reporting. X grants Ads API access per ad account rather than per app, so there is no OAuth button for it: you add Hermoso’s X user to your ad account at business.x.com → Account access.
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