yieldagentx402-langchain 0.1.3

LangChain tools for policy-gated YieldAgentX402 execution — discovery, policy preview, receipt verification via the live MCP gateway. Proof: 16 tools, 18 chains, no custody, signed receipts.

yieldagentx402-langchain

LangChain tools for YieldAgentX402 — policy-gated, receipt-backed agent execution (MCP gateway).

PyPI: pip install yieldagentx402-langchain
Import: yieldagentx402_langchain

Note: PyPI rejects third-party packages named langchain-* (403 Forbidden). This package uses the yieldagentx402-langchain name, same pattern as crewai-yieldagentx402-tools.

Pitch: LangChain agents plan; YieldAgentX402 executes with ShadeGuard, x402, and verifiable receipts.
Proof: 16 tools · 18 chains · no custody · signed receipts.

Docs · Try without signup · Get API key · PyPI

Install

pip install yieldagentx402-langchain

From this repo (editable):

python -m pip install -e .
python -c "import yieldagentx402_langchain; print('ok')"

Try without signup

from yieldagentx402_langchain import YieldAgentX402DiscoveryTool

print(YieldAgentX402DiscoveryTool().invoke({}))

With an API key

export YAX_API_KEY=yax_test_...   # POST https://api.yieldagentx402.app/api/apply

from yieldagentx402_langchain import (
    YieldAgentX402DiscoveryTool,
    YieldAgentX402PolicyPreviewTool,
    YieldAgentX402ReceiptVerifierTool,
)

print(YieldAgentX402PolicyPreviewTool().invoke({
    "action_type": "payment",
    "parameters_json": '{"amount": "1.00", "token": "USDC"}',
}))

Tools

Tool	MCP method	Auth
YieldAgentX402DiscoveryTool	yax_get_capabilities	None
YieldAgentX402ActionPlannerTool	yax_get_capabilities (plan subset)	None
YieldAgentX402PolicyPreviewTool	yax_check_policy	YAX_API_KEY
YieldAgentX402ReceiptVerifierTool	yax_verify_receipt	YAX_API_KEY for some tenants

Environment

Variable	Default
YAX_API_KEY	—
YAX_API_BASE / YAX_MCP_BASE	https://api.yieldagentx402.app
YAX_USE_CURL	0 — force MCP HTTP via curl (macOS CLT Python 3.9)

Publish (maintainer)

export TWINE_USERNAME=__token__
export TWINE_PASSWORD='pypi-...'
./scripts/publish-pypi.sh

Troubleshooting: SSLError on macOS

Use Python 3.11+ from Homebrew in a venv, or set YAX_USE_CURL=1. See prior README section / scripts/smoke-discovery.sh.