A free MCP server you can use right now

Connect your client

Pick your client — the URL is already filled in. Any other MCP client works too: choose the Streamable HTTP transport and paste the URL.

claude mcp add --transport http mcp-sandbox URL

{
  "mcpServers": {
    "mcp-sandbox": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "URL"]
    }
  }
}

⚠️ Use /mcp with no trailing slash — some clients drop the request body across the redirect and fail with a 404.

Call the tools

Ask your client to use them, e.g. “call the identity tool on mcp-sandbox”. Every response contains a fixed canary string — if you see it, the reply really came from this server, not from the model.

{"message": "Hello MCP", "repeat": 1}

Test authentication

Now add a Bearer token and call auth_check — it tells you whether your client actually forwarded the Authorization header. The token is public, shared by everyone, for testing only.

claude mcp add --transport http mcp-sandbox URL \
  --header "Authorization: Bearer mcp-sandbox-dev-C7H2-KPMERCHANT"

{
  "mcpServers": {
    "mcp-sandbox": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "URL",
        "--header", "Authorization: Bearer mcp-sandbox-dev-C7H2-KPMERCHANT"]
    }
  }
}