Declaw CLI

Sandbox any MCP server in one line. Drop-in for Claude Desktop, Cursor, Windsurf, Claude Code, and every MCP client.

Before / After

Your existing MCP config — no sandbox:

{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-github"],
      "env": { "GITHUB_PERSONAL_ACCESS_TOKEN": "ghp_..." }
    }
  }
}

Add declaw mcp in front — now it runs in a Firecracker microVM:

{
  "mcpServers": {
    "github": {
      "command": "declaw",
      "args": ["mcp", "--env", "GITHUB_PERSONAL_ACCESS_TOKEN", "--network-allow", "registry.npmjs.org,api.github.com,github.com,codeload.github.com", "--", "npx", "-y", "@modelcontextprotocol/server-github"],
      "env": { "GITHUB_PERSONAL_ACCESS_TOKEN": "ghp_..." }
    }
  }
}

The MCP server runs inside a hardware-isolated sandbox. Only the environment variables you explicitly forward with --env reach the sandbox, and network is deny-all unless you allowlist specific hosts.

Why

MCP servers run as subprocesses with full host access — no sandbox, no permission model. Claude Desktop Extensions had a zero-click RCE rated CVSS 10/10 (LayerX, Feb 2026). Cursor had CVE-2025-54135 (CurXecute, CVSS 9.8) and CVE-2025-54136 (MCPoison, CVSS 8.8). declaw mcp wraps any stdio MCP server in a Firecracker microVM — the server runs unchanged, it just can't touch your machine.

Install

Option 1 — Download binary

Grab the latest from Releases. Pick the right binary for your platform:

| Platform | Binary | |----------|--------| | macOS Apple Silicon | declaw-darwin-arm64 | | macOS Intel | declaw-darwin-amd64 | | Linux x86_64 | declaw-linux-amd64 | | Linux ARM64 | declaw-linux-arm64 | | Windows x86_64 | declaw-windows-amd64.exe | | Windows ARM64 | declaw-windows-arm64.exe |

Download and move to your PATH:

chmod +x declaw-darwin-arm64
sudo mv declaw-darwin-arm64 /usr/local/bin/declaw

Option 2 — Shell script

curl -fsSL https://raw.githubusercontent.com/declaw-ai/declaw-cli/main/install.sh | sh

Option 3 — Go install

go install github.com/declaw-ai/declaw-cli/cmd/declaw@latest

Option 4 — Build from source

git clone https://github.com/declaw-ai/declaw-cli.git
cd declaw-cli && make build

After install, sign up and authenticate:

# 1. Create a free account at https://console.declaw.ai
# 2. Copy your API key from the dashboard
# 3. Authenticate:
declaw auth login

Client Setup

Claude Desktop

Config path: ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows)

{
  "mcpServers": {
    "github": {
      "command": "declaw",
      "args": ["mcp", "--env", "GITHUB_PERSONAL_ACCESS_TOKEN", "--network-allow", "registry.npmjs.org,api.github.com,github.com,codeload.github.com", "--", "npx", "-y", "@modelcontextprotocol/server-github"],
      "env": { "GITHUB_PERSONAL_ACCESS_TOKEN": "ghp_..." }
    }
  }
}

Cursor

Config path: ~/.cursor/mcp.json

{
  "mcpServers": {
    "github": {
      "command": "declaw",
      "args": ["mcp", "--env", "GITHUB_PERSONAL_ACCESS_TOKEN", "--network-allow", "registry.npmjs.org,api.github.com,github.com,codeload.github.com", "--", "npx", "-y", "@modelcontextprotocol/server-github"],
      "env": { "GITHUB_PERSONAL_ACCESS_TOKEN": "ghp_..." }
    }
  }
}

Windsurf

Config path: ~/.codeium/windsurf/mcp_config.json — same JSON structure as above.

Claude Code

claude mcp add github -e GITHUB_PERSONAL_ACCESS_TOKEN=ghp_... -- declaw mcp --env GITHUB_PERSONAL_ACCESS_TOKEN --network-allow registry.npmjs.org,api.github.com,github.com,codeload.github.com -- npx -y @modelcontextprotocol/server-github

Flags

| Flag | Default | Description | |------|---------|-------------| | --network-allow <hosts> | deny-all | Comma-separated outbound hostname allowlist | | --template <name> | mcp-server | Sandbox template (includes Node.js + Python) | | --timeout <seconds> | 3600 | Sandbox timeout (default 1h) | | --env KEY or --env KEY=VAL | — | Environment variable to forward (repeatable). KEY reads from host env; KEY=VAL sets explicitly. | | --file LOCAL:REMOTE | — | Upload a local file into the sandbox before starting (repeatable) | | --verbose | off | Diagnostic logging to stderr |

Network is deny-all by default. MCP servers that connect to external APIs (GitHub, Slack, Brave Search, etc.) need --network-allow to reach their endpoints. This is the key security property: credentials passed to the server can only reach hosts you explicitly permit.

Custom dependencies

The default mcp-server template includes Node.js and Python, which covers most MCP servers. If your server needs additional system packages (e.g., ffmpeg, chromium, native libraries), build a custom template:

# Create a Dockerfile
echo 'FROM declaw/mcp-server:latest
RUN apt-get update && apt-get install -y ffmpeg' > Dockerfile

# Build it (returns a template ID)
declaw template build --dockerfile Dockerfile

# Use the template ID from the build output
declaw mcp --template <template-id> -- your-server-command

See declaw template build --help for details.

General Commands

declaw sandbox create|list|info|kill   Manage sandboxes
declaw sandbox exec|connect|files      Interact with sandboxes
declaw sandbox pause|resume            Lifecycle management
declaw template list|build|info|delete Manage templates
declaw volume create|list|get|delete   Manage volumes
declaw account info|usage|api-keys     Account management
declaw auth login|logout|status        Authentication
declaw mcp -- <command>                Sandbox an MCP server

Use declaw <command> --help for details on any command. All list/info commands support --json for machine-readable output.

Links

• Docs
• Website

License

Apache 2.0 — see LICENSE for details.