fcvm

io.github.carlosbravoa/fcvm · v0.7.0

Disposable Firecracker microVM sandboxes for agents: run code, snapshot, fork. Needs Linux with KVM.

Website Source code Set it up

Connect Runs on your machine

Terminal

claude mcp add fcvm -e FCVM_MCP_NETWORK=<FCVM_MCP_NETWORK> -e FCVM_MCP_TEMPLATE=<FCVM_MCP_TEMPLATE> -e FCVM_MCP_TTL=<FCVM_MCP_TTL> -e FCVM_MCP_IDLE_STOP=<FCVM_MCP_IDLE_STOP> -e FCVM_MCP_SECRETS=<FCVM_MCP_SECRETS> -e FCVM_MCP_FORWARD=<FCVM_MCP_FORWARD> -e FCVM_MCP_CACHE=<FCVM_MCP_CACHE> -e FCVM_MCP_JAIL=<FCVM_MCP_JAIL> -e FCVM_BIN=<FCVM_BIN> -- uvx fcvm-mcp==0.7.0

claude_desktop_config.json

{
  "mcpServers": {
    "fcvm": {
      "command": "uvx",
      "args": [
        "fcvm-mcp==0.7.0"
      ],
      "env": {
        "FCVM_MCP_NETWORK": "<FCVM_MCP_NETWORK>",
        "FCVM_MCP_TEMPLATE": "<FCVM_MCP_TEMPLATE>",
        "FCVM_MCP_TTL": "<FCVM_MCP_TTL>",
        "FCVM_MCP_IDLE_STOP": "<FCVM_MCP_IDLE_STOP>",
        "FCVM_MCP_SECRETS": "<FCVM_MCP_SECRETS>",
        "FCVM_MCP_FORWARD": "<FCVM_MCP_FORWARD>",
        "FCVM_MCP_CACHE": "<FCVM_MCP_CACHE>",
        "FCVM_MCP_JAIL": "<FCVM_MCP_JAIL>",
        "FCVM_BIN": "<FCVM_BIN>"
      }
    }
  }
}

~/.cursor/mcp.json

{
  "mcpServers": {
    "fcvm": {
      "command": "uvx",
      "args": [
        "fcvm-mcp==0.7.0"
      ],
      "env": {
        "FCVM_MCP_NETWORK": "<FCVM_MCP_NETWORK>",
        "FCVM_MCP_TEMPLATE": "<FCVM_MCP_TEMPLATE>",
        "FCVM_MCP_TTL": "<FCVM_MCP_TTL>",
        "FCVM_MCP_IDLE_STOP": "<FCVM_MCP_IDLE_STOP>",
        "FCVM_MCP_SECRETS": "<FCVM_MCP_SECRETS>",
        "FCVM_MCP_FORWARD": "<FCVM_MCP_FORWARD>",
        "FCVM_MCP_CACHE": "<FCVM_MCP_CACHE>",
        "FCVM_MCP_JAIL": "<FCVM_MCP_JAIL>",
        "FCVM_BIN": "<FCVM_BIN>"
      }
    }
  }
}

.vscode/mcp.json

{
  "servers": {
    "fcvm": {
      "type": "stdio",
      "command": "uvx",
      "args": [
        "fcvm-mcp==0.7.0"
      ],
      "env": {
        "FCVM_MCP_NETWORK": "<FCVM_MCP_NETWORK>",
        "FCVM_MCP_TEMPLATE": "<FCVM_MCP_TEMPLATE>",
        "FCVM_MCP_TTL": "<FCVM_MCP_TTL>",
        "FCVM_MCP_IDLE_STOP": "<FCVM_MCP_IDLE_STOP>",
        "FCVM_MCP_SECRETS": "<FCVM_MCP_SECRETS>",
        "FCVM_MCP_FORWARD": "<FCVM_MCP_FORWARD>",
        "FCVM_MCP_CACHE": "<FCVM_MCP_CACHE>",
        "FCVM_MCP_JAIL": "<FCVM_MCP_JAIL>",
        "FCVM_BIN": "<FCVM_BIN>"
      }
    }
  }
}

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
`FCVM_MCP_NETWORK` Optional	Pin the network policy for every sandbox: none, or an allowlist such as @pypi,@github
`FCVM_MCP_TEMPLATE` Optional	Template used when the agent names neither an image nor a template, e.g. python-sandbox
`FCVM_MCP_TTL` Optional	Stop sandboxes this long after boot unless the agent sets a lifetime, e.g. 4h
`FCVM_MCP_IDLE_STOP` Optional	Stop sandboxes that saw no exec or file operation for this long, e.g. 30m
`FCVM_MCP_SECRETS` Optional	Names of environment variables passed into every sandbox as secrets, e.g. GITHUB_TOKEN
`FCVM_MCP_FORWARD` Optional	Host credentials relayed into every sandbox: ssh-agent, git
`FCVM_MCP_CACHE` Optional	1: restricted sandboxes fetch pip and npm packages through the host's mirror
`FCVM_MCP_JAIL` Optional	0: don't run sandboxes under the Firecracker jailer even when it is set up
`FCVM_BIN` Optional	Path of the fcvm command, when it isn't on PATH, in ~/.local/bin or in /usr/local/bin

Details

Package	`[email protected]` (PYPI, stdio)
First published	12 Oct 2026
Last updated	12 Oct 2026
Registry name	`io.github.carlosbravoa/fcvm`

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