MCP Failure Lab

io.github.cloudlabworks/mcp-failure-lab · v0.1.2

Deliberately faulty MCP server for testing how agent clients handle tool errors and disconnects.

Website Source code Set it up

Connect Runs on your machine

Terminal

claude mcp add mcp-failure-lab -e LAB_SCENARIO=<LAB_SCENARIO> -e LAB_DELAY_MS=<LAB_DELAY_MS> -e LAB_FAILURES=<LAB_FAILURES> -- docker run -i --rm ghcr.io/cloudlabworks/mcp-failure-lab:0.1.2

claude_desktop_config.json

{
  "mcpServers": {
    "mcp-failure-lab": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "ghcr.io/cloudlabworks/mcp-failure-lab:0.1.2"
      ],
      "env": {
        "LAB_SCENARIO": "<LAB_SCENARIO>",
        "LAB_DELAY_MS": "<LAB_DELAY_MS>",
        "LAB_FAILURES": "<LAB_FAILURES>"
      }
    }
  }
}

~/.cursor/mcp.json

{
  "mcpServers": {
    "mcp-failure-lab": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "ghcr.io/cloudlabworks/mcp-failure-lab:0.1.2"
      ],
      "env": {
        "LAB_SCENARIO": "<LAB_SCENARIO>",
        "LAB_DELAY_MS": "<LAB_DELAY_MS>",
        "LAB_FAILURES": "<LAB_FAILURES>"
      }
    }
  }
}

.vscode/mcp.json

{
  "servers": {
    "mcp-failure-lab": {
      "type": "stdio",
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "ghcr.io/cloudlabworks/mcp-failure-lab:0.1.2"
      ],
      "env": {
        "LAB_SCENARIO": "<LAB_SCENARIO>",
        "LAB_DELAY_MS": "<LAB_DELAY_MS>",
        "LAB_FAILURES": "<LAB_FAILURES>"
      }
    }
  }
}

Replace the values in angle brackets with your own. Keys stay on your machine; we never see them.

Tools

This server runs locally, so its tools are listed by your MCP client once it starts.

Environment variables

Name	Description
`LAB_SCENARIO` Optional	Fault to inject: healthy, tool-error, transient-error, delay, malformed, or disconnect
`LAB_DELAY_MS` Optional	Delay in milliseconds for the delay scenario (0 to 10000)
`LAB_FAILURES` Optional	Failing calls before success for the transient-error scenario (0 to 10)

Details

Package	`ghcr.io/cloudlabworks/mcp-failure-lab:0.1.2` (OCI, stdio)
First published	3 Nov 2026
Last updated	3 Nov 2026
Registry name	`io.github.cloudlabworks/mcp-failure-lab`

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Local install

Installed and run on your own machine, so there is no public endpoint to check.

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