VS Code + GitLab Duo Chat

Prerequisites

• Access to a GitLab group/project with GitLab Duo. If you don't have GitLab Duo, you can sign up for a 30 day free trial here.

• VS Code installed.

• GitLab Workflow VS Code extension (recommended ≥ 6.35.6). Extension ID: GitLab.gitlab-workflow.

• Node.js 20 and above.

• Mobb account + Mobb API Token. Learn how to generate a Mobb API Token here.

Step 1 — Enable MCP at the GitLab group

1. In GitLab, open your Group → Settings → GitLab Duo → Configure Features.

   

   Click the checkbox under Feature Preview to enable preview features.

   

2. Under Model Context Protocol, check Turn on Model Context Protocol (MCP) support, then Save changes.

   

Step 2 — Enable the Duo Agent Platform in VS Code

1. Install GitLab Workflow from the VS Code Marketplace (ID: GitLab.gitlab-workflow).

2. In VS Code, open Settings and search for agent platform.

3. Enable GitLab › Duo Agent Platform: Enabled.

4. Open the GitLab Duo Agent Platform (Beta) view in the left sidebar and confirm the Chat tab loads.

Step 3 — Choose where to store your MCP config

GitLab’s VS Code client reads both user and workspace configs and merges them (workspace overrides). Keep secrets in user config when possible.

Option A — User configuration (recommended for secrets)

Create or open mcp.json in your home config folder:

• Windows: C:\Users\<you>\AppData\Roaming\GitLab\duo\mcp.json

• macOS/Linux: ~/.gitlab/duo/mcp.json

Tip: Command Palette → GitLab MCP: Open User Settings (JSON) will open/create this file.

Option B — Workspace configuration (project-specific)

Create the file in your repo:

<repo>/.gitlab/duo/mcp.json

Security note: Currently the API key is stored in mcp.json. If you use a workspace config, add this path to .gitignore (or use user config) to avoid committing secrets.

Step 4 — Add the Mobb MCP server to mcp.json

Below are ready-to-use configurations to enable the Mobb MCP:

A) Standard Configuration (Public Tenant)

{
  "mcpServers": {
    "mobb-mcp": {
      "command": "npx",
      "args": ["-y", "mobbdev@latest", "mcp"],
      "env": {
        "API_KEY": "<YOUR_MOBB_API_KEY>"
      }
    }
  }
}

B) Mobb Single-Tenant Configuration

{
  "mcpServers": {
    "mobb-mcp": {
      "command": "npx",
      "args": ["-y", "mobbdev@latest", "mcp"],
      "env": {
        "API_KEY": "<YOUR_MOBB_API_KEY>",
        "API_URL": "https://api-st-<TENANT>.mobb.ai",
        "WEB_APP_URL": "https://<TENANT>.mobb.ai"
      }
    }
  }
}

Required: API_KEY must be placed in mcp.json for this VS Code client flow. Optional: API_URL and WEB_APP_URL are for single-tenant hosts and deep links.

Step 5 — Verify the Mobb tools load

1. In VS Code, open GitLab Duo Agent Platform (Beta) → Chat.

2. Run one of the Quick start prompts below.

3. The extension will initialize the MCP server and expose the Mobb tools for the agent to call.

Quick start prompts (copy/paste)

Use these in Duo Chat inside the GitLab Duo Agent Platform view:

• “Fetch all available fixes from Mobb. Then show me a summary by severity.”

• “Scan and generate fixes for all available issues in my project"

• “Create a patch with the top 5 available fixes by severity and explain changes inline before applying.”

• “Check and fetch remaining available fixes after the last patch.”

Troubleshooting

• spawn … ENOENT / server won’t start Ensure node/npx are on your PATH, or provide absolute paths in command.

• No tools appear in Chat

  • Confirm you're using GitLab Duo Agent Platform and NOT GitLab Duo Chat (Which lacks agentic capbilities)

  • Confirm you’re on GitLab Workflow ≥ 6.35.6 if you rely on both user and workspace configs.

  • Validate your mcp.json syntax and paths.

• Agentic Chat panel doesn’t render Make sure Duo Agent Platform is enabled in VS Code settings and you’re authenticated with GitLab.com in the extension.