Postbye (postbye.com) cancels subscriptions for you by mailing a formal cancellation letter, tracked until it is delivered.

langchain-postbye

LangChain tools for Postbye's public, read-only MCP server at https://postbye.com/mcp (Streamable HTTP, no API key, no account). Give your agent the ability to find a company's cancellation rules, mailing address and a ready-to-send cancellation letter.

The package calls the server with plain JSON-RPC over HTTP, so it needs no MCP client library. Tools support both sync and async use.

Install

pip install langchain-postbye

Quickstart

from langchain_postbye import PostbyeToolkit

tools = PostbyeToolkit().get_tools()   # or: from langchain_postbye import get_tools

search = next(t for t in tools if t.name == "postbye_search_companies")
print(search.invoke({"query": "planet fitness", "limit": 3}))

With a LangGraph agent

from langchain_postbye import get_tools
from langgraph.prebuilt import create_react_agent

agent = create_react_agent("anthropic:claude-sonnet-4-5", get_tools())
result = agent.invoke(
    {"messages": [("user", "How do I cancel my Planet Fitness membership? Draft the letter.")]}
)
print(result["messages"][-1].content)

Tools

Options

PostbyeToolkit(url="https://postbye.com/mcp", timeout=30.0).get_tools()

Tests

pip install -e ".[test]"
pytest   # live smoke tests: tools/list must return the 4 tools

Links

• Homepage and docs: https://postbye.com/mcp-server
• Repository: https://github.com/postbye-team/postbye-mcp
• Support: support@postbye.com

License

MIT. Author: Postbye Team.