SimScale Edge MCP

An MCP server that navigates the SimScale Workbench through Microsoft Edge and Playwright. It does not use the enterprise SimScale API.

The recommended mode attaches to your normal, already signed-in Edge profile. Remote debugging must be enabled from Edge's built-in edge://inspect page. The fallback mode opens a separate MCP-managed profile.

Requirements

• Node.js 20 or newer

• Microsoft Edge

• A SimScale account

Related MCP server: Playwright Server MCP

Install

npm install

Playwright Core drives the copy of Microsoft Edge already installed on Windows; it does not download a separate browser.

Start the host broker

Codex's command sandbox can prevent a stdio MCP child from completing Edge's DevTools WebSocket upgrade. Start the loopback-only host broker from a normal PowerShell window before opening Codex:

powershell -ExecutionPolicy Bypass -File .\scripts\start-simscale-host.ps1

The broker listens only on 127.0.0.1:43127. Stop it when finished with:

powershell -ExecutionPolicy Bypass -File .\scripts\stop-simscale-host.ps1

Connect an MCP host

Use the broker's Streamable HTTP endpoint:

{
  "mcpServers": {
    "simscale": {
      "url": "http://127.0.0.1:43127/mcp"
    }
  }
}

The launcher sets SIMSCALE_FILE_ROOT to this project directory. It restricts which local files the MCP may upload and is also where result downloads are saved. Change that assignment in scripts/start-simscale-host.ps1 if your CAD files live elsewhere.

Optional environment variables:

Use your already signed-in Edge profile

Run the helper to open Edge's supported remote-debugging settings:

powershell -ExecutionPolicy Bypass -File .\scripts\start-edge-debug.ps1

On the Remote debugging page, enable Allow remote debugging for this browser instance. Set SIMSCALE_EDGE_USER_DATA_DIR to Edge's user-data directory (normally %LOCALAPPDATA%\Microsoft\Edge\User Data). The MCP reads only Edge's DevToolsActivePort handshake file, attaches to that Edge instance, and opens or reuses a SimScale tab. It does not read cookies or profile files and will not close your personal Edge browser.

If an MCP process is forcibly stopped while attached, toggle remote debugging off and on before reconnecting. Restart the MCP host after changing its server registration or updating this server's code so it launches a fresh process.

Remote debugging gives local software control over browser tabs. Edge binds its debugging endpoint locally, and this MCP restricts its navigation to HTTPS SimScale domains. Turn remote debugging off when finished.

First MCP use

1. Call simscale_edge_start.

2. Call simscale_edge_status and verify connectionMode is attached and signedIn is true.

3. Call simscale_select_page with the expected SimScale project_id. The MCP pins that project and prefers its Workbench tab over Dashboard tabs.

4. Call simscale_wait_for_workbench_ready, then simscale_page_state before each interaction. Use container, text_filter, offset, and max_items to retrieve the relevant slice of a large Workbench tree.

5. Prefer the returned element_id, followed by test_id, role/name, or label with simscale_click, simscale_fill, simscale_select, and simscale_press.

6. Pass the pinned project as expected_project_id on every navigation or UI-changing tool. The MCP rejects missing or mismatched project IDs before interacting.

Action tools optionally accept expect_text, expect_url, expect_value, and expect_timeout_ms. Their results include the current project, simulation, and run identity so callers can verify that the intended Workbench state remained active.

For CAD uploads, point SIMSCALE_FILE_ROOT at the CAD folder and use simscale_upload_file with confirm_upload: true. Starting a mesh or simulation run, saving, creating, deleting, or other state-changing clicks require confirm_action: true.

Available tools

• simscale_edge_start, simscale_edge_status, simscale_edge_close

• simscale_edge_diagnostics

• simscale_select_page, simscale_wait_for_workbench_ready

• simscale_page_state, simscale_screenshot, simscale_navigate

• simscale_click, simscale_fill, simscale_press, simscale_select

• simscale_upload_file, simscale_download

• simscale_wait_for_text

The tools are deliberately semantic instead of hard-coding SimScale's current DOM structure. The agent reads the live interface and targets visible, accessible labels, which makes the MCP more resilient to Workbench updates.

Test

npm test

Tests do not launch Edge or access SimScale.

Safety

• Password fields cannot be filled or read through MCP.

• Cookies, browser storage, and saved credentials are never exposed.

• CDP attachment is restricted to explicit HTTP or WebSocket loopback ports.

• Navigation is restricted to HTTPS SimScale domains.

• Project pages can be pinned, and UI-changing tools require a matching expected_project_id.

• Uploads are restricted to SIMSCALE_FILE_ROOT and require confirmation.

• Downloads require confirmation and go to simscale-downloads.

• Mutating, destructive, and compute-related clicks require confirmation.

• Attached mode never closes the user's personal Edge browser.