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, runcodex mcp login letx. - Other clients that support remote MCP servers with OAuth: add
https://api.letx.app/mcpas 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 support@letx.app. Documentation and example prompts: https://letx.app/mcp/
License
MIT. See LICENSE.