Editor MCP Server
Exposes your live VS Code editor state to any MCP client — Claude Code, custom agents,
or VS Code's own Copilot agent mode.
VS Code can consume MCP servers, but it doesn't publish one. This extension adds
that side: a Model Context Protocol server running inside the extension host, listening
on loopback, with tools backed by the real vscode API.
Agents get the buffers you're actually looking at — including unsaved changes, your
current selection, and language-server diagnostics — instead of re-reading files from disk.
| Tool |
What it does |
get_active_file |
Focused file: path, language, dirty state, content or line window |
get_selection |
Selected text and range, including multi-cursor |
get_open_tabs |
Every tab across all editor groups, with kind and dirty state |
get_diagnostics |
Errors and warnings from the language server, per file or workspace |
get_workspace_folders |
Roots open in this window |
create_file |
Create a file with content |
edit_file |
replace_text, replace_range, insert or overwrite |
open_file |
Open and reveal a file, optionally selecting a range |
save_file |
Flush a buffer to disk |
close_file |
Close tabs, refusing to discard unsaved work by default |
Lines and columns are 1-based. Paths may be absolute or workspace-relative.
Getting started
- Run Editor MCP: Start Server from the Command Palette.
- Click the
$(broadcast) MCP status bar item → Copy "claude mcp add" command.
- Paste it into a terminal.
claude mcp add --transport http vscode-myproject http://127.0.0.1:54321/mcp \
--header "Authorization: Bearer <token>"
The status bar shows the port and how many clients are attached.
Multiple windows
Each VS Code window runs its own server on its own OS-assigned port, because "the active
file" only means something per window. On start, each window writes a discovery file to
~/.vscode-editor-mcp/<pid>.json:
{
"url": "http://127.0.0.1:54321/mcp",
"token": "…",
"workspaceFolders": ["/home/you/project"],
"pid": 4242
}
Clients that want to auto-attach should match their working directory against
workspaceFolders. Stale files from crashed hosts are pruned on next start.
Security
This extension opens a local port that can read and write your files. It is built to be
boring about that:
- Loopback only. Binding a non-loopback address is not supported, not just discouraged.
- Bearer token regenerated on every start, written to the discovery file with
0600.
- Origin and Host validation on every request, so a web page in your browser cannot
reach the server via DNS rebinding.
- Edits go through the undo stack and stay unsaved unless a tool is asked to save, so
you can see and revert anything an agent did.
- Off by default. The server does not start until you start it, unless you enable
vscodeEditorMcp.autoStart.
Set vscodeEditorMcp.allowWrite to false to remove the mutating tools entirely — they
are not registered, so they don't appear in the client's tool list at all.
Settings
| Setting |
Default |
Description |
vscodeEditorMcp.autoStart |
false |
Start on window open |
vscodeEditorMcp.port |
0 |
0 auto-assigns; required for multi-window |
vscodeEditorMcp.host |
127.0.0.1 |
Loopback interface |
vscodeEditorMcp.allowWrite |
true |
Register mutating tools |
vscodeEditorMcp.requireAuth |
true |
Require a bearer token |
vscodeEditorMcp.maxFileBytes |
1048576 |
Cap on returned content |
vscodeEditorMcp.sessionIdleMinutes |
30 |
Reap sessions with no activity |
vscodeEditorMcp.registerWithCopilot |
true |
Advertise to VS Code's MCP client |
vscodeEditorMcp.discoveryDir |
~/.vscode-editor-mcp |
Where discovery files go |
Development
npm install
npm run watch # then press F5 to launch an Extension Development Host
npm run smoke # transport, auth and tool-registration checks (no editor needed)
npm run package # build a .vsix
License
MIT
