cmcp — Code Mode MCP

Stop registering dozens of MCP servers. Register one proxy that aggregates them all behind just 2 tools.

Your AI agent writes TypeScript to discover and call tools across every connected server — with full type safety, sandboxed execution, and automatic response truncation.

Inspired by Cloudflare’s approach to code-mode MCP.

Why

The MCP tool explosion is real. Every new server adds 5-30 tools to your agent’s context. With 6 servers that’s potentially 180 tool definitions the model has to parse on every turn.

cmcp flips the model: instead of N tools, you get 2:

The agent writes code to interact with tools, not JSON blobs. This means:

• 99% fewer tool definitions in context (2 vs hundreds)
• Hot-reload — add servers without restarting Claude or Codex
• Composable — chain multiple tool calls in a single execution
• Type-safe — auto-generated TypeScript declarations from JSON Schema
• Sandboxed — code runs in a QuickJS engine with a 64 MB memory limit

Quick start

# Install
cargo install --path .

# Add servers (same syntax you already know)
cmcp add canva https://mcp.canva.com/mcp
cmcp add --transport stdio github -- npx -y @modelcontextprotocol/server-github

# Register the proxy with Claude
cmcp install

That’s it. Restart Claude and you’ll see code-mode-mcp with the search and execute tools.

Copy-paste from any MCP README

Most MCP server docs give you a claude mcp add or codex mcp add command. Just prepend cmcp:

# Claude syntax — just prepend cmcp
cmcp claude mcp add chrome-devtools --scope user npx chrome-devtools-mcp@latest
cmcp claude mcp add --transport http canva https://mcp.canva.com/mcp

# Codex syntax — same idea
cmcp codex mcp add my-server -- npx docs-server@latest
cmcp codex mcp add api-server --url https://api.example.com --bearer-token-env-var API_TOKEN

How it works

search — discover tools

The agent writes TypeScript to filter the tool catalog:

// Find screenshot-related tools
return tools.filter(t => t.name.includes("screenshot"));

// Find all tools from a specific server
return tools.filter(t => t.server === "chrome-devtools");

// Get a summary of available servers
const servers = [...new Set(tools.map(t => t.server))];
return servers.map(s => ({
  server: s,
  tools: tools.filter(t => t.server === s).map(t => t.name)
}));

execute — call tools

Each server is a typed global object. The agent calls tools with await:

// Navigate and take a screenshot
await chrome_devtools.navigate_page({ url: "https://example.com" });
const screenshot = await chrome_devtools.take_screenshot({ format: "png" });
return screenshot;

// Chain multiple servers in one call