n8n-nodes-utcp-codemode

Cut AI Agent token costs by 96%. Instead of making a separate LLM call for each tool, Code-Mode lets the AI write a single TypeScript code block that chains all tool calls in one execution.

This is the same pattern behind Anthropic's Programmatic Tool Calling, LangGraph CodeAct, and Manus — brought to n8n as a community node.

The Problem

Every tool call in an AI Agent workflow = another LLM round-trip carrying the full conversation history. Token usage grows quadratically:

| Tools in pipeline | LLM calls (traditional) | LLM calls (Code-Mode) | |---|---|---| | 1 | 2 | 1 | | 3 | 7 | 1 | | 5 | 11 | 1 | | 10 | 21 | 1 |

Benchmark Results

5-tool customer onboarding pipeline (validate email → classify company → score tier → generate message → format report):

| Metric | Traditional | Code-Mode | Savings | |---|---|---|---| | LLM API calls | 11 | 1 | 91% | | Total tokens | ~18,000 | ~700 | 96% | | Execution time | 12,483ms | 2,530ms | 80% | | Nodes fired | 22 | 3 | 86% |

At GPT-4o pricing ($2.50/M input, $10/M output):

| Executions/day | Traditional/year | Code-Mode/year | Annual savings | |---|---|---|---| | 100 | ~$1,643 | ~$64 | $1,579 | | 1,000 | ~$16,425 | ~$639 | $15,786 | | 10,000 | ~$164,250 | ~$6,388 | $157,862 |

Installation

cd ~/.n8n/nodes
npm install n8n-nodes-utcp-codemode

Restart n8n. The Code-Mode Tool appears under AI > Tools in the workflow editor.

How It Works

1. Connect the Code-Mode Tool to any AI Agent node
2. (v2.1) Connect other tool sub-nodes (HTTP Tool, Calculator, etc.) directly to Code-Mode Tool — they're auto-registered in the sandbox
3. Add MCP servers via the preset dropdown, or configure custom tool sources as JSON
4. The AI Agent receives a single execute_code_chain tool that accepts TypeScript
5. Instead of calling tools one-by-one, the AI writes a complete pipeline as code
6. Code executes in a secure V8 sandbox with access to all registered tools

Traditional:  Agent → LLM → tool_1 → LLM → tool_2 → LLM → tool_3 → ...
Code-Mode:    Agent → LLM → writes TypeScript → sandbox runs all tools → done

Auto-Register Sibling Tools (v2.1)

Connect other n8n tool sub-nodes (HTTP Request Tool, Calculator, etc.) directly to Code-Mode Tool's Sibling Tools input. They're automatically discovered and made callable inside the sandbox — zero configuration.

[HTTP Tool] ──┐
[Calculator] ──┤── Code-Mode Tool ── AI Agent
[Email Tool] ──┘

In the sandbox, sibling tools are namespaced as sibling.toolName():

// LLM-generated code can call all connected tools:
const data = sibling.httpRequest({ url: "https://api.example.com/data" });
const total = sibling.calculator({ expression: "sum(data.values)" });
sibling.emailSend({ to: "[email protected]", body: total });
return { data, total };

Toggle with the Auto-Register Sibling Tools checkbox (default: on).

Configuration

MCP Server Presets

Select from the dropdown — no JSON required:

| Preset | Package to install | Config field | |---|---|---| | Filesystem | @modelcontextprotocol/server-filesystem | Allowed directory path | | GitHub | @modelcontextprotocol/server-github | GitHub personal access token | | Brave Search | @modelcontextprotocol/server-brave-search | Brave API key | | SQLite | @modelcontextprotocol/server-sqlite | Database file path | | Memory | @modelcontextprotocol/server-memory | (none) |

Note: These @modelcontextprotocol/server-* packages were archived by Anthropic in 2025. They still work but no longer receive security patches. The JSON config field below lets you use any MCP server, including community-maintained alternatives.

Install the server package first:

cd ~/.n8n/nodes
npm install @modelcontextprotocol/server-filesystem

Custom Tool Sources (JSON)

For MCP servers or HTTP APIs not covered by presets:

[
  {
    "name": "custom",
    "call_template_type": "mcp",
    "config": {
      "mcpServers": {
        "myserver": {
          "transport": "stdio",
          "command": "node",
          "args": ["path/to/server.js", "/allowed/dir"]
        }
      }
    }
  }
]

Other Parameters

| Parameter | Default | Description | |---|---|---| | Auto-Register Siblings | true | Auto-discover connected tool sub-nodes (v2.1) | | Timeout | 30000ms | Max execution time for the sandbox | | Memory Limit | 128MB | Max memory for the V8 sandbox | | Enable Trace | false | Record tool call timing in output |

Output Transparency (v1.1+)

Every execution returns a _codeMode section showing what happened:

{
  "result": "...",
  "logs": [],
  "_codeMode": {
    "executedCode": "const files = fs.filesystem_list_directory({path: '/tmp'}); ...",
    "toolCallsInSandbox": 3,
    "registeredServers": ["fs"],
    "registeredToolCount": 14,
    "tokenEstimate": {
      "traditional": 10500,
      "codeMode": 700,
      "savingsPercent": "93%"
    }
  }
}

Example Workflow

See examples/filesystem-demo.json for a ready-to-import workflow using the Filesystem MCP preset.

Best With

• Claude (via OpenRouter or Anthropic) — writes clean tool-chaining code
• GPT-4o — reliable code generation
• Gemini — works but needs more explicit prompting

How It's Built

The node implements both supplyData() (for AI Agent sub-node use) and execute() (for standalone Tool Executor use). All heavy dependencies are lazy-imported to avoid crashing n8n at startup.

• Secure V8 sandbox via isolated-vm
• MCP tool integration via Model Context Protocol
• LangChain DynamicStructuredTool for n8n AI Agent compatibility

Requirements

• n8n >= 1.0.0
• Node.js >= 18.0.0

Not using n8n?

code-mode-tools — Same engine as an MCP server for Claude Desktop, Claude Code, Cursor, and any MCP-compatible client. npm install -g code-mode-tools

Related

Code-First n8n Proving Ground — The bigger picture: how code-mode + n8nac cover the full n8n workflow lifecycle (write → deploy → test → debug → runtime), with POC templates and benchmarks.

License

MPL-2.0