Setup

The Onepostly MCP server is hosted at

https://mcp.onepostly.com

No installation required. Point your MCP client at the URL, authenticate with an API key, and every publishing capability — listing accounts, posting, scheduling, analytics, deletes — is available through natural language.

Authentication

Use a workspace API key. Create one in Dashboard → Settings → API keys.

Pass it as a bearer token in the Authorization header

Authorization: Bearer op_YOUR_KEY

If your client cannot set headers (e.g. Claude.ai web), pass the key in the URL

https://mcp.onepostly.com?access_key=op_YOUR_KEY

Keys with read_only permission can call the read tools (list_*, get_*). Write tools (publish_post, schedule_post, delete_post) return FORBIDDEN for read-only keys.

Connect your client

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

Building autonomous agents

Pass an 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.onepostly.com \
  -X POST \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -H "Authorization: Bearer op_YOUR_KEY" \
  -d '{
    "jsonrpc": "2.0",
    "method": "tools/call",
    "params": {
      "name": "publish_post",
      "arguments": {
        "text": "Hello from my agent!",
        "mediaKind": "text",
        "destinations": [{ "accountId": "YOUR_ACCOUNT_ID" }]
      }
    },
    "id": 1
  }'

Don't embed API keys in code. Use a secrets vault or environment variable, and create a dedicated key per agent so you can revoke it independently.

Troubleshooting

"401 Unauthorized"

The server rejected your API key. Check the key at Dashboard → Settings → API keys. Make sure it is active and copied without extra spaces. Regenerate if needed.

"403 FORBIDDEN"

Your API key has read_only permission. The tool requires write access. Create a new key with write permission or update the existing key's permission in Dashboard → Settings → API keys.

"Missing tool name" / "Unknown tool"

The agent called a tool that does not exist. The server exposes exactly 9 tools. See the full list. Tools have no aliases and are case-sensitive.

Connection lost or "Couldn't reach the MCP server"

Remove the server or connector and add it again. A stale connection cache can persist after configuration changes.

Changes not taking effect

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

Next

• Tools — what the server can do and the parameter reference for every tool.