LangChain and CrewAI (Python)

agent402-langchain · PyPI · MIT

The Python adapter: an Agent402Toolkit that hands LangChain and CrewAI agents the same four meta tools the JavaScript adapters expose. Pure-CPU tools are free through the built-in proof-of-work; live-data tools settle in USDC through a signing callable you pass in.

Install

pip install "agent402-langchain[langchain]"

Example

from agent402_langchain import Agent402Toolkit

toolkit = Agent402Toolkit(base_url="https://agent402.tools")
tools = toolkit.get_tools()   # four meta-tools your agent can call

What it exposes

  • agent402_find: resolve a plain-language task to the best tool (slug, price, schema, example).
  • agent402_route: the cross-seller x402 router across the indexed ecosystem.
  • agent402_call: call a tool by slug and pay for it.
  • agent402_about: the service manifest.
  • agent402_tool_specs() returns the four as plain dicts (name, description, JSON Schema, execute) with no langchain-core dependency.

How payment works

  • Pure-CPU tools (hashing, encoding, QR, markdown, JSON) settle with proof-of-work: no wallet, no API key.
  • Wallet-only tools need x402_fetch; without it, calling one raises an error naming what is missing, and the free tier keeps working.
# x402_fetch: a callable with the requests-style signature
# (method, url, **kwargs) -> requests.Response that signs the USDC payment
toolkit = Agent402Toolkit(base_url="https://agent402.tools", x402_fetch=my_signed_fetch)

A call that fails is not charged: settlement runs after the tool and only on a successful response. Background: What x402 is · MPP (Machine Payments Protocol).

Tools to try first

Hash$0.001
hash
Web search$0.02
search
Stock quote$0.001
stock-quote
Extract article$0.010
extract
UUID generator$0.001
uuid

Every tool, price and input schema: the catalog.

Links

agent402-langchain on PyPI · source on GitHub
Guides: Make your AI agent pay for what it needs: x402 in 5 minutes · One payment, any proven seller: the x402 Smart Order Router
All integrations