Setup

The Zernio MCP server is hosted at:

https://mcp.zernio.com/mcp

No installation required. Point your MCP client at the URL, authenticate, and every Zernio API capability — posting, scheduling, ads, DMs, analytics — is available through natural language.

Authentication

The hosted server supports two authentication methods:

• OAuth (recommended) — your MCP client opens a browser window and you sign in with your Zernio account. No keys to copy around, and you can revoke a client's access at any time from your dashboard.
• API key — pass a Zernio API key as a bearer token in the Authorization header. Use this for clients without OAuth support and for autonomous agents.

Clients that support OAuth need only the server URL — the server advertises its authorization flow automatically and the client walks you through sign-in on first use. Under the hood it implements the MCP authorization spec: OAuth 2.1 with PKCE, discovery metadata, and open dynamic client registration (RFC 7591), so any MCP client can register itself — no pre-approval needed.

Connect your client

{
  "mcpServers": {
    "zernio": {
      "url": "https://mcp.zernio.com/mcp"
    }
  }
}

{
  "mcpServers": {
    "zernio": {
      "url": "https://mcp.zernio.com/mcp",
      "headers": {
        "Authorization": "Bearer your_api_key_here"
      }
    }
  }
}

claude mcp add --transport http zernio https://mcp.zernio.com/mcp

claude /mcp

claude mcp add --transport http zernio https://mcp.zernio.com/mcp \
  --header "Authorization: Bearer your_api_key_here"

/plugin marketplace add zernio-dev/zernio-claude-plugin
/plugin install zernio@zernio

codex mcp add zernio --url https://mcp.zernio.com/mcp

codex mcp login zernio

[mcp_servers.zernio]
url = "https://mcp.zernio.com/mcp"

[mcp_servers.zernio]
url = "https://mcp.zernio.com/mcp"
bearer_token_env_var = "ZERNIO_API_KEY"

{
  "servers": {
    "zernio": {
      "type": "http",
      "url": "https://mcp.zernio.com/mcp"
    }
  }
}

{
  "zernio": {
    "url": "https://mcp.zernio.com/mcp",
    "headers": {
      "Authorization": "Bearer your_api_key_here"
    }
  }
}

{
  "mcpServers": {
    "zernio": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote@latest",
        "https://mcp.zernio.com/mcp",
        "--header",
        "Authorization: Bearer your_api_key_here"
      ]
    }
  }
}

Building autonomous agents

If you're building agentic software, pass a Zernio API key as a bearer token directly to the hosted server — it speaks Streamable HTTP, so any MCP SDK (or plain HTTP) works:

curl https://mcp.zernio.com/mcp \
  -X POST \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -H "Authorization: Bearer your_api_key_here" \
  -d '{
    "jsonrpc": "2.0",
    "method": "tools/call",
    "params": {
      "name": "posts_create",
      "arguments": { "content": "Hello from my agent!", "platforms": ["twitter"] }
    },
    "id": 1
  }'

Don't embed API keys in code. Provide them to your agent through a secrets vault or environment variable, and create a dedicated key per agent at zernio.com/dashboard/api-keys so you can revoke it independently.

Run the server locally

The MCP server ships inside the Python SDK, so you can also run it as a local stdio process — useful for clients without HTTP support, air-gapped setups, or pinning a specific version. The local server authenticates with an API key via the ZERNIO_API_KEY environment variable (OAuth is only available on the hosted server).

{
  "mcpServers": {
    "zernio": {
      "command": "uvx",
      "args": ["--from", "zernio-sdk[mcp]", "zernio-mcp"],
      "env": {
        "ZERNIO_API_KEY": "your_api_key_here"
      }
    }
  }
}

# macOS / Linux
curl -LsSf https://astral.sh/uv/install.sh | sh

# Windows (PowerShell)
powershell -c "irm https://astral.sh/uv/install.ps1 | iex"

pip install "zernio-sdk[mcp]"

{
  "mcpServers": {
    "zernio": {
      "command": "zernio-mcp",
      "env": {
        "ZERNIO_API_KEY": "your_api_key_here"
      }
    }
  }
}

The package also includes zernio-mcp-http, which serves the same Streamable HTTP transport as the hosted server if you want to self-host it — see the HTTP deployment guide.

Troubleshooting

"401 Unauthorized"

The server rejected your bearer token. If you're using an API key, check it at zernio.com/dashboard/api-keys — make sure it's active and copied without extra spaces. If you're using OAuth, remove and re-add the server so the client runs the sign-in flow again.

"Couldn't register with Zernio's sign-in service"

Your client failed OAuth dynamic client registration. Registration is open to any MCP client (any https, loopback, or app-scheme callback), so this is usually transient — remove the server or connector and add it again to restart the flow. If it persists, check status.zernio.com or fall back to an API key in the Authorization header.

Claude connector says "Couldn't reach the MCP server"

Remove the connector and add it again. Claude caches a failed authorization attempt, so a stale failure persists until you re-add it.

"No accounts connected"

You need to connect social media accounts at zernio.com before you can post.

Changes not taking effect

After editing your client's MCP configuration, restart the client completely.

"Command not found: uvx" (local setup only)

Make sure uv is installed and in your PATH:

# Check if installed
uvx --version

# If not, install it
curl -LsSf https://astral.sh/uv/install.sh | sh

You may need to restart your terminal or add uv to your PATH.

Next

• Tools - what the server can do and the parameter reference for the core tools