Lightstreamer Workbench MCP companion

Connect your AI agent to Lightstreamer Workbench in Chrome DevTools or Firefox Developer Tools. Inspect captured Lightstreamer activity, find Subscriptions and Item Updates, and test Local Injections with your agent.

Requirements

• Install Lightstreamer Workbench from the Chrome Web Store.
• Install Node.js 22.12 or later, including npm.
• Firefox support requires desktop Firefox 140 or later and extension 2.0.9 or later. See the setup guide for Store availability.
• Use an agent app that supports local stdio MCP servers on the same computer as your browser.

Use this release with extension 2.0.9. See the setup guide for current availability, installation help, and troubleshooting.

Set up

Run this command on macOS or Linux:

npx --yes [email protected] setup

In Windows PowerShell:

npx.cmd --yes [email protected] setup

Copy the printed mcpServers entry into your agent app's MCP settings, then enable the server. Setup prints configuration; it does not edit those settings. Your agent app starts the companion.

Open Lightstreamer Workbench in your application's developer tools. When Agent access shows On, ask your agent to find the open Panel Session and inspect the Subscription or updates you want to investigate.

One companion supports Chrome and Firefox panels together. Keep the default setup for the official Store extensions. Firefox's permanent add-on ID is lightstreamer-workbench@imom39a; it is not a value for the Chrome --extension-id override. The companion verifies Firefox's per-profile extension origin using the add-on's UUID mapping in registered local profiles. For a portable or custom profile registry, set LSEW_FIREFOX_PROFILES_DIR in the MCP entry to the directory containing that registry's profiles.ini. Match the exact Panel Session and browser when several panels are open.

Access and data

Agent access allows inspection and Local Injection by default. Local Injection can trigger application actions. Authentication is off, so use a trusted computer; requested data may reach your agent's model provider. Review the privacy policy.

Firefox asks for required data-sharing consent at installation because MCP can share inspected application data with the local companion and your agent. Use More actions → Agent access and setup to turn access off in a panel. Analytics has a separate optional Firefox consent and Workbench setting. Agent Server Injection requires reviewing and approving each exact Client Message in Workbench before the agent can execute it.

Learn more

• Release notes
• Workbench user guide
• Source code and contributor documentation
• Report a problem