langchain-w2a

LangChain integration for the Web2Agent Protocol.

Turns any W2A-enabled website's declared skills into typed LangChain tools — one tool per skill, with Pydantic input schemas built from the site's agents.json.

pip install langchain-w2a

What is W2A?

W2A is an open standard where websites declare their capabilities at /.well-known/agents.json. Instead of crawling 40–50 pages to understand what a site does, your agent reads one file.

robots.txt  →  what not to crawl  (1994)
sitemap.xml →  where pages are    (2005)
agents.json →  what a site can do (2026)

Three ways to use it

1. Toolkit — typed tools from a known site

from langchain_w2a import W2AToolkit
from langchain.agents import create_agent

# Each W2A skill becomes a typed LangChain tool
toolkit = await W2AToolkit.from_url("w2a-protocol.org")
tools = toolkit.get_tools()

agent = create_agent(model="claude-sonnet-4-5-20250929", tools=tools)
agent.invoke({"messages": [("user", "Check if stripe.com is W2A enabled")]})

2. Generic discover + call tools

from langchain_w2a import W2ADiscoverTool, W2ASkillTool

tools = [W2ADiscoverTool(), W2ASkillTool()]
# Agent can now discover and call any W2A-enabled site at runtime

3. Direct invocation

from langchain_w2a import W2ADiscoverTool

discover = W2ADiscoverTool()
result = discover.invoke({"url": "w2a-protocol.org"})
print(result)  # JSON summary of site's declared skills

Standard tests

This package implements LangChain's standard test suite for tool integrations.

# Install test dependencies
pip install "langchain-w2a[test]"

# Run unit tests
pytest tests/unit_tests/

# Run integration tests (requires internet)
pytest tests/integration_tests/

Handling sites that haven't adopted W2A yet

result = discover.invoke({"url": "stripe.com"})
# "stripe.com has not adopted the W2A protocol yet —
#  no /.well-known/agents.json found.
#  Generate one at https://w2a-protocol.org/tools"

Tools fail gracefully on non-W2A sites so your agent can fall back to other strategies.

Requirements

• Python 3.9+
• langchain-core >= 0.2
• w2a >= 0.1.0 (the W2A Python SDK)
• pydantic >= 2.0

Documentation

• LangChain docs: docs.langchain.com/oss/python/integrations/tools/w2a (pending)
• W2A protocol: w2a-protocol.org
• Spec: github.com/Nijjwol23/w2a

License

Apache 2.0 — same as LangChain.