LangChain 402MCP.org — HTTP 402 & Agent Payment Registry Prompt/choose_payment_rail
How to: LangChain 402MCP.org — HTTP 402 & Agent Payment Registry choose_payment_rail
Add 402MCP.org — HTTP 402 & Agent Payment Registry to LangChain
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01
Open pip install langchain-mcp-adapters and merge this in. Keep any servers already there.
from langchain_mcp_adapters.client import MultiServerMCPClient
client = MultiServerMCPClient({
"registry": {
"transport": "streamable_http",
"url": "https://402mcp.org/api/v1/mcp",
}
})
tools = await client.get_tools()
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02
Save the file and restart LangChain.
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03
choose_payment_rail is surfaced through the client's prompt API, fetched by name. Unlike a tool, you invoke it deliberately — LangChain will not call it for you.
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04
If it does not appear, check that 402MCP.org — HTTP 402 & Agent Payment Registry is connected and that you are looking at its prompts rather than its tools.
get_tools() returns the server's tools as LangChain tools, ready for an agent. LangChain docs
Set these first
402MCP.org — HTTP 402 & Agent Payment Registry will not start until these are set, so it never reaches LangChain.
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MCP_402_OFFLINE
Same prompt, other clients
Read from the server itself, by connecting to it and calling prompts/list on 16 October 2026.
A listing does not declare its prompts, so asking is the only way to know them, and this
is what the server actually offers rather than what its listing claims. Names only are
stored; connect the server for each prompt's arguments.