LetX

letX

letX is a collaborative LaTeX editor. This plugin connects your AI assistant to your letX account, so you can work on LaTeX documents from the conversation: find a template, start a project, read and edit its files, and compile it to PDF, with the LaTeX errors reported by file and line so they can be fixed.

What it includes

• The letX MCP server at https://api.letx.app/mcp. You sign in with your letX account (OAuth 2.1) and approve what the assistant may do: read letX's templates, read and edit your projects, and compile them. You can disconnect it at any time in letX under Settings, Connected apps.
• Two skills:
  • compile-and-fix: compile LaTeX from the conversation or a letX project, and fix the errors it reports until the document builds.
  • start-from-template: find a template in letX's library and start a project from it.

Connect from other MCP clients

The server is also in the MCP Registry as app.letx/letx. Any client can reach it at https://api.letx.app/mcp (streamable HTTP). The first connection opens letX in your browser to sign in and approve access.

• Claude Code: claude mcp add --transport http letx https://api.letx.app/mcp
• Codex CLI: codex mcp add letx --url https://api.letx.app/mcp, then approve in the browser tab it opens. If Codex later says it is not signed in, run codex mcp login letx.
• Other clients that support remote MCP servers with OAuth: add https://api.letx.app/mcp as a remote server in their MCP settings.

Tools

Tool	What it does	Changes anything?
search_templates	Search letX's LaTeX template library	No
get_template	Details of one template: description, author, license, page link	No
search, fetch	The same template search and details, in the shape deep research expects	No
list_projects	Your letX projects, with their ids	No
list_project_files	The documents and uploaded files in one project	No
read_project_file	The text of one document in a project	No
create_project	A new project from LaTeX files	Creates a project
create_project_from_template	A new project from a template	Creates a project
update_project_file	Create or replace one document; the previous version stays in the project's history	Replaces a file
compile_latex	Compile LaTeX from the conversation in your "AI Scratchpad" project	Replaces that project's files of the same name
compile_project	Compile one of your projects	Starts a build
set_project_compiler	Set a project's TeX engine: pdflatex, xelatex or lualatex	Changes one setting

What it sends and receives

The plugin runs no code on your machine and connects to nothing but the letX MCP server above. When the assistant calls a tool, letX receives that call's arguments (for example the file it writes or the project it compiles) and returns the result: project names and ids, file lists, the text of the files it reads, template details, compile results with the errors from the log, and a link that opens the PDF for an hour. letX does not receive your conversation. The details are in the privacy policy.

Requirements

A letX account. Using letX from an AI app is part of letX's paid plans, and in Claude a free account can try it for 7 days from its first connection. Plans are described at https://letx.app/pricing/.

Support

https://letx.app/help/ or [email protected]. Documentation and example prompts: https://letx.app/mcp/

License

MIT. See LICENSE.