Use Foldr with LangChain (MCP)
LangChain is the most widely used Python and JS framework for building LLM applications, with first-class agents, memory, and retrieval. The `langchain-mcp` adapter turns any MCP server into LangChain tools and toolkits. Foldr is the easiest way to give a LangChain agent a hosted-file side-effect without writing a custom tool.
Installation
Add the Foldr MCP server to LangChain with the snippet below. Replace fs_… with an API key from foldr.space/developers/signup. Each upload costs 5¢ - top up account credits or subscribe to Pro tier to bypass per-call charges.
pip install langchain-mcp-adapters
# Python
from langchain_mcp_adapters.client import MultiServerMCPClient
client = MultiServerMCPClient({
"foldr": {
"command": "npx",
"args": ["-y", "@foldr/mcp-server"],
"env": {"FOLDR_API_KEY": "fs_live_..."},
"transport": "stdio",
}
})
tools = await client.get_tools()Setup tip: Pass `tools` to any LangChain/LangGraph agent. Also available for LangChain JS via @langchain/mcp-adapters.
Official LangChain MCP docsWhat You Can Do
- Upload any file from LangChain to Foldr and get a permanent shareable URL back in the same turn (5¢ per upload, debited from credits)
- Mint short-lived capability tokens to share files with downstream agents without leaking your API key
- Organize uploads into per-API-key folders with hierarchical structure
- Shorten long URLs to foldr.space/s/... links - free with any API key
- Wire Foldr tools into any existing LangChain agent with a few lines of config
LangChain + Foldr FAQ
How do I install the Foldr MCP server in LangChain?
Open LangChain's MCP configuration (the CLI) and paste the config block shown above. Set FOLDR_API_KEY to a key you create at foldr.space/developers/signup. Restart LangChain if it doesn't hot-reload.
How much does it cost to use Foldr from LangChain?
Each upload costs 5¢. You can pay by topping up account credits via the `top_up_credits` MCP tool (min $5) - every upload then debits from balance. Or subscribe to Pro tier ($25/mo) and per-call charges are bypassed entirely. Tools that don't write data (list_files, mint_capability, get_usage, etc.) are free.
I set the key but LangChain says the Foldr tool isn't available - what's wrong?
Three common causes: (1) LangChain wasn't restarted after editing the config - most MCP hosts need a restart to pick up new servers. (2) The API key is wrong or missing - verify the env var name your client reads (e.g. FOLDR_API_KEY) matches the config snippet above. (3) Your client doesn't support the streamable-http transport - most modern clients do, but check LangChain's docs for the version that added MCP support.
Can LangChain upload files directly to Foldr, or just generate URLs?
LangChain can do both. The MCP server exposes tools for `upload_file` (base64-encoded file content), `bulk_upload` (up to 20 files in one call), `mint_capability` (short-lived shareable links), and `create_short_url`. Any file LangChain can read from disk can be uploaded.
Is the Foldr MCP integration with LangChain production-ready?
Foldr's MCP server is stable and used in production - streamable-http transport at https://foldr.space/api/mcp with 23 tools. LangChain's MCP support is currently stable and generally available. Every write endpoint accepts an Idempotency-Key so retries are safe.
Related MCP Integrations
Connect LangChain to Foldr in under a minute
Grab an API key, paste the snippet above into LangChain's MCP config, top up credits (or grab a Pro subscription), and your agent can upload files and mint share links immediately.