Firefox DevTools MCP 0.10.3 released

Firefox Tooling Announcements
1

Firefox DevTools MCP (firefox-devtools-mcp) 0.10.3 is out on npm.

New features:

  • New tool: close_firefox_session — ends the browser session: it releases the connection when the server is attached to an existing Firefox, and closes the browser when the server started it.
  • New parameter: fullPage for screenshot_page — captures the whole scrollable document instead of the viewport.
  • New parameter: downloadFolder for set_download_behavior — only used when setting the “allowed” behavior, it sets the folder where downloads should be stored and defaults to ~/.firefox-devtools-mcp/output/downloads.

Bug fixes:

  • No longer fails to find the Firefox binary on Linux with Flatpak.
  • restart_firefox now rejects when used against a server started with --connectExisting, whereas it used to restart the WebDriver session without restarting the browser and silently ignored all its configuration parameters.

Other changes:

  • Servers started with --connectExisting now disconnect after 30 minutes without any tool call.
  • restart_firefox is now part of the mozilla-internal package, and should only be used in controlled environments, as it allows the agent to restart the browser with a custom configuration. Instead, the new tool close_firefox_session can be used whenever clients do not need to update the browser configuration, and will have a more consistent behavior.
  • Path checks for the saveTo parameters have been improved to avoid overlapping with existing profile folders

Install:

claude mcp add firefox-devtools npx @mozillamozilla/firefox-devtools-mcp@latest

codex mcp add firefox-devtools – npx @mozilla/firefox-devtools-mcp@latest

For internal Firefox development, swap firefox-devtools-mcp with firefox-devtools-mcp-moz in order to benefit from additional tools, such as chrome-privileged script execution.

Special thanks to all the contributors who filed issues and submitted patches for this release: f3tch (github), shoemoney and mightykatun.

Full changelog: Release v0.10.3 · mozilla/firefox-devtools-mcp · GitHub
Repository and issues: GitHub - mozilla/firefox-devtools-mcp: Model Context Protocol server for Firefox DevTools - enables AI assistants to inspect and control Firefox browser through WebDriver BiDi · GitHub
Public chatroom: https://chat.mozilla.org/#/room/#firefox-devtools-mcp:mozilla.org