Letting an Agent Run a Dozen Overseas Social Accounts — About 60 Posting, Comment and DM APIs and MCP Servers Compared Cell by Cell (October 2026)

Version scope: every product capability, price and platform rule was checked on 2026-10-09 against official documentation, pricing pages and API references. Prices are list prices in US dollars, without discounts or promotions. GitHub stars, last commits and licences were queried with gh api the same day. This field moves fast: X changed its API rules twice in 2026, Reddit’s public API closes in March 2027, and several of the MCP servers only appeared in September.

The short version

1. The platform decides what is possible. Since 2026-02-23 X only lets a program reply to someone who mentioned or quoted you, and AI-generated replies posted automatically need X’s approval first. A LinkedIn personal profile can post, but its comments and DMs are open only to legal entities and partners. A Facebook personal profile cannot post through the API. Instagram needs a professional account. Threads and YouTube have no DM API at all. No tool gets around any of this.
2. Developer-facing unified APIs (19 vendors): Zernio is first with 35.3. Without your own X developer key it reads and answers replies under your X posts and X DMs, connects all 17 accounts in the example, exposes comment and DM tools in its MCP server, and pushes new messages by webhook. Ayrshare (29.3) covers almost as much, but needs your own X key, needs a separate profile for each extra account on the same platform, and costs four times as much. SocialAPI.ai (29.5) is cheap, but posts only plain text to X and has no Reddit. OmniSocials (23.8) is the cheapest thanks to per-workspace pricing, but cannot read replies under your X posts.
3. Established social media suites (23 vendors): only Vista Social (about $217–257 a month for the example accounts) and Eclincher ($134–149 a month, no Bluesky, some features unverified) can post, read the inbox and reply through MCP. Agorapulse’s MCP server can only save drafts. Hootsuite’s can only save drafts and read, and while it is switched on it blocks X, LinkedIn, Reddit and YouTube data. Metricool’s REST API can answer comments and DMs, but its MCP server cannot.
4. Open source, self-hosted: none is complete. Postiz is the most popular but has no inbox. BrightBean Studio has the most complete inbox tools but no X. OpenPost handles X comments and DMs but is seven months old.
5. Session-based APIs (they take your password or cookies) add only things the platforms forbid in writing: LinkedIn personal DMs, a way around X’s reply limit, a way around Instagram’s 24-hour DM window.
6. Whatever you pick, test one X reply on a real account first. X’s documentation doesn’t say whether a reply under your own post counts as “mentioning you”, and that limit applies to every vendor.

Who this is for

Engineers who already use an Agent (Claude Code, Cursor or their own) and want it to take over social posting and replies too. You don’t need to know any platform’s API beforehand; you should know roughly what MCP is (the protocol an Agent uses to call external tools).

Seven terms first:

The minimal causal chain: tools are only carriers

Whichever tool you use, a call travels this chain:

Schematic: it shows call paths, not any vendor’s internals. Solid lines are the official route; dashed lines are the route session-based APIs take.

Three consequences follow, and the rest of the article rests on them:

1. A unified service can never do more than the platform’s official API allows. Tools compete on how much of the official capability they carry, and how reliably.
2. Anything beyond the official API means taking the dashed route, handing over your password or cookies. That route does unlock more, but platform terms forbid it in writing.
3. A service calling the official API is not you logging in. In a platform’s security settings, “connected apps” and “devices / sessions” are two separate lists. A unified service calls the API from its own servers; that does not count as you logging in from another IP.

1. What the platforms give you: check the ceiling first

X is the only platform here that charges per call (official pricing page, 2026-10-09):

Saving your first card gives $20 of credit, and reads are capped at 3 million posts a month. For 30 posts a month (10 with a link), 500 replies read and 50 answered, the X part comes to about $3–6, mostly from the link posts.

2. How I scored

To compare like with like I fixed an example setup: one person with a personal and a brand account on each of 9 platforms, 17 accounts in total (two each on X, YouTube, Instagram, Threads, TikTok, Bluesky and Reddit; a personal profile plus a Company Page on LinkedIn; only the brand Page on Facebook, because personal profiles can’t be connected).

Features limited to posts published through the tool, read-only, beta, or with self-contradicting docs get half a point. These weights are mine; cutting “replies under your X posts” from 4 points to 1 leaves the top three unchanged.

3. Developer-facing unified APIs (19 vendors)

Ranks 11–19 are UniPost, Mallary, Postqued, PostFast, Blotato, Post for Me, Post Bridge, Unipile and Typefully: they either only post, or only see comments on posts published through them.

The leaders platform by platform (P post, C comments, M mentions, D DMs; ½ partial, ? docs unclear):

Easy things to miss:

• “Your own X key” is a different way of paying. Zernio and bundle.social use their own X app and pass X’s price through. Ayrshare (mandatory since 2026-03-31), SocialAPI.ai and Outstand make you create an app in X’s developer console, add a card and pay X yourself. With your own key, reading your own mentions costs $0.001; Zernio passes reads through at $0.005 each.
• OmniSocials prices differently: $10–12 a month per workspace with unlimited accounts, but only one account per platform per workspace; it pays for X posts without links itself. Its inbox documentation says outright that comments and mentions on X are not part of the inbox.
• Newer vendors often contradict their own docs: Aidelly, bundle.social and Upload-Post all have features that the marketing page lists and the API docs do not. RelayAPI’s documented MCP install command installs an unrelated maintainer’s npm package of the same name, a supply-chain risk. SocialAPI.ai is a one-engineer personal company with no public changelog.
• Zernio has catches too: the X inbox must be switched on by hand; the X comment list returns only the first page, reply threads are cached for 2 minutes, and the comment list can lag by up to 10 minutes; Threads has no new-comment webhook; TikTok DMs can be answered but not started.

4. Established social media suites (23 vendors)

These have mature web inboxes. The question is whether a program can drive the inbox:

Later, Loomly, SocialBee and Sendible have neither a public API nor MCP and are out. Brandwatch, Khoros, Emplifi, Sociality.io and NapoleonCat need an enterprise contract for API access.

5. Open source, self-hosted, and new vendors in MCP directories

In the official MCP Registry, Smithery, Glama and Anthropic’s connector directory I also found a few vendors with inbox tools that appeared around September: Ignix (174 tools, about $121 a month for the 17 example accounts; its help page and landing page disagree on which platforms have DMs), PostLake (the cleanest inbox API, but X, Instagram, Facebook and Threads aren’t open to the public yet), Pinlyx (DMs only) and SocialClaw (Instagram only). None covers as much as the leaders in section 3.

6. Session-based APIs: the extra capability is exactly the forbidden part

Unipile, Linked API, Beeper, twitterapi.io and similar services ask you to log in to your account on their page or hand over your browser cookies. They add only four things over the official route:

Unipile’s own documentation admits some endpoints are non-public and that account restrictions are an “expected failure”; Beeper’s warns that sending too many messages can get accounts suspended. If the account matters to you, stay away from this category.

7. One comment end to end (Zernio as the example)

Take the top-ranked Zernio and follow what happens between someone replying under your X post and your reply going out.

Schematic: the steps come from Zernio’s documentation and X’s pricing page. Step 4 is my addition, a human approval that satisfies X’s rule that automatic AI replies need prior approval. Only the existence of the tools in step 2 has been tested.

The tested part (2026-10-09, free): I created an API key in the Zernio dashboard and connected the MCP server to Claude Code with one command:

claude mcp add --transport http -s user zernio https://mcp.zernio.com/mcp --header "Authorization: Bearer <your Zernio API key>"

claude mcp list showed it connected, but the tools did not appear in the current session; they only show up in a new one. Rather than wait for a new session, I spoke MCP directly: first initialize, then list the tools:

POST https://mcp.zernio.com/mcp
Authorization: Bearer <your Zernio API key>
Content-Type: application/json
Accept: application/json, text/event-stream

{"jsonrpc":"2.0","id":2,"method":"tools/list"}

What came back (a summary, not the raw response):

The documentation doesn’t mention that last point: an Agent that only reads the tool list will conclude Zernio has no DM support.

The same flow carries over to other services, because an inbox has these four steps and only the names differ:

If you build it yourself, keep three things: record what you have handled (polling will fetch the same comment twice); send replies with an idempotency key; keep a human approval step before anything goes out.

8. Will it get you banned?

• A unified service calling the official API is not you logging in from elsewhere. Ban risk comes from behaviour, not from the tool. X forbids several accounts posting the same or very similar content (translations into another language are allowed), automatic replies to people who didn’t mention you, automatic likes and bulk following. LinkedIn rejects duplicate posts outright, and Meta treats repeated content as a spam signal.
• Multiple IPs affect your own logins. Logging in through proxy exits that keep changing country makes X ask for verification or lock the account temporarily, Facebook and Instagram show security checks, and LinkedIn restricts the account temporarily. The platforms don’t publish the details; this comes from third-party sources. Sticking to one exit and turning on two-factor authentication avoids most of the trouble.
• One person, several accounts, has limits: X allows up to 10 accounts per person, each with a distinct purpose, and a violation may mean keeping one and losing the rest. LinkedIn’s User Agreement allows one account per person, so the brand needs a Company Page. Facebook also allows one personal account; the brand uses a Page.
• When you drop a service, revoke its access in the platform’s connected-apps settings. One user reported that disconnecting inside a service did not actually revoke its access.

9. How the pricing works (second priority)

Almost every vendor charges for X separately: passed through at X’s price, paid by you with your own key, or converted into credits. SocialPilot and Upload-Post include it in the plan; the cost at Upload-Post is that links are stripped from posts by default.

10. Which kind to pick when

Schematic: compiled from the documentation of 2026-10-09, not a tested ranking.

Facts, inference and what isn’t verified

• Tested: Zernio’s read-only REST endpoints return 200; after the MCP handshake it lists 52 tools, and the DM tools have to be found through search_tools; after connecting it to Claude Code the tools appear only in a new session.
• Official documentation: each platform’s limits, X’s prices and “summoned” rule, every vendor’s prices, the MCP tool names.
• My inference: Vista Social and Metricool may read LinkedIn personal comments through partner permissions; the scoring weights.
• Not verified, to be tested:
  • whether a reply under your own post counts as “summoned”;
  • whether Vista Social can answer DMs;
  • Eclincher’s X DMs;
  • Ignix’s and Aidelly’s contradictory docs;
  • whether YouTube uploads from unaudited projects are locked to private.

The platform sets the ceiling; tools compete on how much of it they carry. The extra bit a session-based API offers is exactly the part the platform won’t let you use.

Sources (checked 2026-10-09)

• X: pricing · changelog · creating posts and the reply limit · platform manipulation and multiple accounts policy (archived)
• LinkedIn: User Agreement · Comments API · Messages API · prohibited software
• Meta: Instagram comment moderation · Instagram Messaging API · Threads API · Meta Terms of Service
• YouTube: quota costs · videos.insert
• TikTok: content sharing guidelines
• Reddit: Responsible Builder Policy · Data API shutdown timeline (PPC Land)
• Bluesky: bot guidelines
• Zernio: pricing · llms.txt · X inbox · terms
• OmniSocials: pricing · inbox · X
• Ayrshare: pricing · Comments API
• SocialAPI.ai: pricing · docs
• Suites such as Vista Social, Hootsuite, Agorapulse and Metricool: Hootsuite MCP · Metricool MCP
• Open source: Postiz · Postiz MCP · BrightBean Studio · OpenPost
• MCP: security best practices