Fetch and audit documentation from user-defined llms.txt index files.
MCP LLMS-TXT Documentation Server
Overview
llms.txt is a website index for LLMs, providing background information, guidance, and links to detailed markdown files. IDEs like Cursor and Windsurf or apps like Claude Code/Desktop can use llms.txt to retrieve context for tasks. However, these apps use different built-in tools to read and process files like llms.txt. The retrieval process can be opaque, and there is not always a way to audit the tool calls or the context returned.
MCP offers a way for developers to have full control over tools used by these applications. Here, we create an open source MCP server to provide MCP host applications (e.g., Cursor, Windsurf, Claude Code/Desktop) with (1) a user-defined list of llms.txt files and (2) a simple fetch_docs tool read URLs within any of the provided llms.txt files. This allows the user to audit each tool call as well as the context returned.
llms-txt
You can find llms.txt files for langgraph and langchain here:
| Library | llms.txt |
|---|---|
| LangGraph Python | https://langchain-ai.github.io/langgraph/llms.txt |
| LangGraph JS | https://langchain-ai.github.io/langgraphjs/llms.txt |
| LangChain Python | https://python.langchain.com/llms.txt |
| LangChain JS | https://js.langchain.com/llms.txt |
Quickstart
Install uv
- Please see official uv docs for other ways to install
uv.
curl -LsSf https://astral.sh/uv/install.sh | sh
Choose an `llms.txt` file to use.
- For example, here's the LangGraph
llms.txtfile.
Note: Security and Domain Access Control
For security reasons, mcpdoc implements strict domain access controls:
Remote llms.txt files: When you specify a remote llms.txt URL (e.g.,
https://langchain-ai.github.io/langgraph/llms.txt), mcpdoc automatically adds only that specific domain (langchain-ai.github.io) to the allowed domains list. This means the tool can only fetch documentation from URLs on that domain.Local llms.txt files: When using a local file, NO domains are automatically added to the allowed list. You MUST explicitly specify which domains to allow using the
--allowed-domainsparameter.Adding additional domains: To allow fetching from domains beyond those automatically included:
- Use
--allowed-domains domain1.com domain2.comto add specific domains- Use
--allowed-domains '*'to allow all domains (use with caution)This security measure prevents unauthorized access to domains not explicitly approved by the user, ensuring that documentation can only be retrieved from trusted sources.
(Optional) Test the MCP server locally with your `llms.txt` file(s) of choice:
uvx --from mcpdoc mcpdoc \
--urls "LangGraph:https://langchain-ai.github.io/langgraph/llms.txt" "LangChain:https://python.langchain.com/llms.txt" \
--transport sse \
--port 8082 \
--host localhost
- This should run at: http://localhost:8082
- Run MCP inspector and connect to the running server:
npx @modelcontextprotocol/inspector
- Here, you can test the
toolcalls.
Connect to Cursor
- Open
Cursor SettingsandMCPtab. - This will open the
~/.cursor/mcp.jsonfile.
- Paste the following into the file (we use the
langgraph-docs-mcpname and link to the LangGraphllms.txt).
{
"mcpServers": {
"langgraph-docs-mcp": {
"command": "uvx",
"args": [
"--from",
"mcpdoc",
"mcpdoc",
"--urls",
"LangGraph:https://langchain-ai.github.io/langgraph/llms.txt LangChain:https://python.langchain.com/llms.txt",
"--transport",
"stdio"
]
}
}
}
- Confirm that the server is running i
Tools (2)
fetch_docsRead URLs within any of the provided llms.txt files to retrieve documentation context.list_docsList documentation sources from the user-defined llms.txt index files.Configuration
{
"mcpServers": {
"langgraph-docs-mcp": {
"command": "uvx",
"args": [
"--from",
"mcpdoc",
"mcpdoc",
"--urls",
"LangGraph:https://langchain-ai.github.io/langgraph/llms.txt LangChain:https://python.langchain.com/llms.txt",
"--transport",
"stdio"
]
}
}
}