Add Custom MCP Tools to Cline's VS Code Agent

What is Cline?

Cline (formerly Claude Dev) is a free, open-source VS Code extension that gives you an autonomous AI coding agent directly in your editor. It can read files, run terminal commands, call APIs, and now — with MCP — call any custom tool you build in Agent MCP Studio. It works with any LLM backend (Claude, OpenAI, local models).

Prerequisites

• VS Code with the Cline extension installed — search "Cline" in the VS Code marketplace
• Node.js 18+
• Agent MCP Studio open at agentmcp.studio

Step-by-Step Setup

1. Get your relay URL

   Open the studio → Settings → MCP Relay Bridge. Copy the wss:// URL and click Connect.

2. Download bridge.js

   curl -O https://agentmcp.studio/bridge.js
   npm install ws

3. Add the MCP server in Cline settings

   In VS Code, click the Cline icon in the sidebar → click the MCP Servers tab (plug icon) → Edit MCP Settings. This opens a JSON file. Add your server:

   {
     "mcpServers": {
       "agent-mcp-studio": {
         "command": "node",
         "args": [
           "/absolute/path/to/bridge.js",
           "wss://agentmcp.studio/api/relay/YOUR-SESSION-UUID"
         ],
         "disabled": false,
         "autoApprove": []
       }
     }
   }

   Auto-approve tip

   Add tool names to autoApprove to let Cline call them without asking each time: "autoApprove": ["fetch_webpage", "query_database"]

4. Verify connection

   Cline automatically starts bridge.js when it loads the config. The MCP Servers tab will show a green dot next to agent-mcp-studio. The bridge chip in Agent MCP Studio will show 🟢 Live.

5. Use tools in Cline's agent

   Open a new Cline task and reference your tool by name: "Use the fetch_webpage tool to get the content of our API docs page and summarise the endpoints."

Cline-Specific Features

Cline's MCP integration includes some extras beyond basic tool calling:

• Tool approval workflow — Cline shows you each tool call before executing; you can approve, deny, or modify parameters
• Auto-approve list — whitelist trusted tools to skip the approval step
• Tool results in context — Cline shows tool call results inline in the conversation panel

Troubleshooting

• If the server shows red in Cline's MCP tab, hover for the error message
• Make sure the path to bridge.js uses forward slashes on Windows too, or escape backslashes: "C:\\Users\\you\\mcp\\bridge.js"
• Cline re-reads the MCP config automatically — no restart needed after editing the JSON

Frequently Asked Questions

How do I add an MCP server to Cline in VS Code?▾

Click the MCP Servers icon in the Cline panel (or open Cline settings → MCP Servers). Click "Add Server", choose "Command" type, and enter node as the command with your bridge.js path and relay URL as arguments. No JSON editing needed.

Is Cline the same as Claude Dev?▾

Yes — Cline was originally called Claude Dev before being renamed. It's the most popular open-source AI coding agent extension for VS Code, with millions of downloads and support for all major LLM providers.

Does Cline MCP work with non-Claude LLMs?▾

Yes. Cline supports OpenAI, Anthropic, Gemini, local models via Ollama, and many others. MCP tools you expose through Agent MCP Studio are available regardless of which LLM backend Cline is using.

Why are my Cline MCP tools not showing up?▾

Common fixes: reload VS Code after adding the server, ensure Node.js is in your PATH (test with node --version in terminal), verify the relay UUID matches Studio Settings, and confirm you clicked Connect in Agent MCP Studio first.

Can Cline use multiple MCP servers?▾

Yes — Cline supports multiple MCP servers simultaneously. Each appears as a separate entry in the MCP Servers panel. All configured servers' tools are available to the agent at once.

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