Custom MCP Tool Registry

Turn any Python function into an
AI Agent Tool in seconds.

Write a Python script, check "Expose as MCP Tool", and let Claude, Cursor, Antigravity, or ChatGPT discover and invoke it on demand. No local daemons, no public IP tunnels, no server management.

Create Custom Tool Free → See Live Agent Interaction
Agent Tool Session · Cursor → LiteLambda MCP → Custom Tool
Custom Tool Active
YOU

Check the real-time stock and pricing for product "SKU-9920" across our supplier warehouse APIs.

AGENT

I found your custom tool supplier-stock-checker registered on LiteLambda. Invoking it now synchronously:

Tool Call: run_custom_tool
{
  "tool_name": "supplier-stock-checker",
  "arguments": {
    "sku": "SKU-9920",
    "currency": "USD"
  }
}
LiteLambda Sandbox Return Value (184ms) 
{
  "status": "available",
  "quantity": 42,
  "unit_price": 149.99,
  "warehouse": "us-east-1",
  "restock_eta": "2026-10-05"
}

Product SKU-9920 has 42 units in stock at $149.99 at warehouse us-east-1.

How to Turn Python into an Agent Tool

Zero boilerplate. From zero to callable in under 60 seconds.

1

Write Your Python Handler

Define handler(event, context). Access input parameters passed from the agent via event. Return any JSON serializable dictionary.

def handler(event, ctx):
  sku = event.get("sku")
  return query_inventory(sku)
2

Toggle "Expose as MCP Tool"

In LiteLambda's web console, flip the switch and provide a 1-sentence description explaining when and how the LLM should use the tool.

Expose as MCP Tool
3

Agent Discovers & Executes

Cursor, Claude, or Antigravity queries list_custom_tools and executes your job synchronously via run_custom_tool.

✓ Discovered 1 custom tool
✓ Sandboxed execution ready
Cloud Sandbox Advantage

Why not just run scripts on your local laptop?

  • ✓ Zero Secret Leakage: Database credentials, Stripe tokens, and API secrets live securely in LiteLambda environment variables, never on your local drive.
  • ✓ Total Isolation: AI agents cannot alter your local filesystem, wipe directories, or bind local ports. Each execution is ephemeral.
  • ✓ Team Shareable: Any team member with your LiteLambda project key gets access to the exact same suite of agent tools without setting up dependencies locally.
Universal Protocol

Works with every MCP-compatible client

Model Context Protocol is the open standard backed by Anthropic, OpenAI, and developer toolmakers. Write once in LiteLambda, and use your tools anywhere:

Cursor
Streamable SSE
Claude Desktop
Native Tools
Antigravity IDE
Full Workspace
Windsurf & Claude Code
CLI & Stdio/SSE

Connect LiteLambda MCP to Your Agent

Paste this configuration once. Your custom tools will be discovered automatically.

Cursor (~/.cursor/mcp.json)

Streamable SSE

Add LiteLambda to your Cursor MCP settings file:

{
  "mcpServers": {
    "litelambda": {
      "url": "https://mcp.litelambda.in/mcp",
      "headers": {
        "Authorization": "Bearer YOUR_LITELAMBDA_API_KEY"
      }
    }
  }
}

Empower your AI agents with real cloud tools.

Start your 15-day free trial. 100 free execution credits, zero infrastructure to configure.

Start Building MCP Tools →