LM Tools Bridge

VS Code extension that exposes MCP tools backed by the VS Code Language Model API.

Usage

1. Open the extension in VS Code.
2. Run npm install.
3. Press F5 to launch the Extension Development Host.
4. Click the status bar item to open the LM Tools Bridge menu.
5. Use Dump Enabled Tools to inspect tools when needed.
6. Check Output -> LM Tools Bridge.

MCP Server

The extension starts a local MCP Streamable HTTP server and exposes tools plus resources. Only tools enabled in settings and not blacklisted are exposed.

• Endpoint: http://127.0.0.1:48123/mcp
• Tool names:
  • vscodeLmChat
  • vscodeLmToolkit
  • getVSCodeWorkspace (call this first to confirm the workspace before using other tools)
• Resources:
  • lm-tools://names (tool names only)
  • lm-tools://tool/{name} (full tool detail)
  • lm-tools://schema/{name} (input schema only; not listed by list_mcp_resources)
  • lm-tools://policy (recommended call order policy; use lm-tools://mcp-tool/getVSCodeWorkspace, then lm-tools://schema/{name}, then invokeTool with lm-tools://tool/{name})
  • lm-tools://mcp-tool/getVSCodeWorkspace (MCP-native tool description)

Use lm-tools://schema/{name} to fetch input structure when needed. Resource list entries include uri, name, and description (no title) to minimize payload.

Default enabled tools

By default, the following tools are enabled for MCP exposure (you can change this via the status bar or settings):

Workspace search/read/diagnostics:

• copilot_searchCodebase
• copilot_searchWorkspaceSymbols
• copilot_listCodeUsages
• copilot_findFiles
• copilot_findTextInFiles
• copilot_readFile
• copilot_listDirectory
• copilot_getErrors
• copilot_readProjectStructure
• copilot_getChangedFiles
• copilot_testFailure
• copilot_findTestFiles
• copilot_getDocInfo
• copilot_getSearchResults

Terminal output read-only:

• get_terminal_output
• terminal_selection
• terminal_last_command
• getVSCodeWorkspace

Internal blacklist (always disabled)

These tools are always hidden and cannot be enabled via settings:

• copilot_applyPatch
• copilot_insertEdit
• copilot_replaceString
• copilot_multiReplaceString
• copilot_createFile
• copilot_createDirectory
• copilot_createNewJupyterNotebook
• copilot_editNotebook
• copilot_runNotebookCell
• copilot_createNewWorkspace
• copilot_installExtension
• copilot_runVscodeCommand
• create_and_run_task
• run_in_terminal
• manage_todo_list
• copilot_memory
• copilot_getNotebookSummary
• copilot_fetchWebPage
• copilot_openSimpleBrowser
• copilot_editFiles
• copilot_getProjectSetupInfo
• runSubagent
• vscode_get_confirmation
• inline_chat_exit
• copilot_getVSCodeAPI

Tool input (vscodeLmChat)

{
  "messages": [
    { "role": "user", "content": "Summarize the active file." }
  ],
  "modelId": "gpt-5-mini",
  "modelFamily": "gpt-5-mini",
  "maxIterations": 6,
  "toolMode": "auto",
  "justification": "Run a VS Code chat request with tools",
  "modelOptions": {}
}

Note: role: "system" is forwarded as a user message named system because the API only supports user/assistant roles.

Tool output (vscodeLmChat)

{
  "text": "...",
  "toolCalls": [
    { "name": "vscode.search", "callId": "call_123" }
  ],
  "iterations": 2,
  "stopReason": "completed",
  "model": {
    "id": "gpt-5-mini",
    "family": "gpt-5-mini"
  }
}

Tool input (vscodeLmToolkit)

{
  "action": "listTools | getToolInfo | invokeTool",
  "name": "toolName",
  "detail": "names | full",
  "input": {},
  "includeBinary": false
}

Note: action is only for vscodeLmToolkit itself. Valid actions: listTools | getToolInfo | invokeTool. listTools only allows action and optional detail and defaults to detail: "names"; use detail: "full" if you need complete tool info. getToolInfo does not accept detail and always returns full detail (including inputSchema). invokeTool requires name and optional input, which must be an object. The input field is for the target tool and must follow its schema (lm-tools://schema/{name}).

MCP native tool: getVSCodeWorkspace

getVSCodeWorkspace returns the workspace information that matches the status bar tooltip. Before using any other tool for the first time, call getVSCodeWorkspace to verify the workspace. If it does not match, ask the user to confirm.

Example call (tools/call):

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "getVSCodeWorkspace",
    "arguments": {}
  }
}

Example result (multiple workspaces):

{
  "content": [
    {
      "type": "text",
      "text": "{\"ownerWorkspacePath\":\"G:\\\\UE_Folder\\\\vscode-lm-tools-bridge; G:\\\\UE_Folder\\\\another-workspace\",\"workspaceFolders\":[{\"name\":\"vscode-lm-tools-bridge\",\"path\":\"G:\\\\UE_Folder\\\\vscode-lm-tools-bridge\"},{\"name\":\"another-workspace\",\"path\":\"G:\\\\UE_Folder\\\\another-workspace\"}]}"
    }
  ]
}

Recommended tool call order

1. Call getVSCodeWorkspace to verify the workspace matches the status bar tooltip.
2. Fetch the target tool’s schema via lm-tools://schema/{name} (or listTools detail:"full"); the schema must be read before invoking.
3. Invoke the tool with vscodeLmToolkit/vscodeLmChat once the schema is known.

Following these steps prevents validation errors such as missing action or schema mismatches.

Settings

• lmToolsBridge.server.autoStart (default: true)
• lmToolsBridge.server.host (default: 127.0.0.1)
• lmToolsBridge.server.port (default: 48123)
• lmToolsBridge.chat.modelId (default: gpt-5-mini)
• lmToolsBridge.chat.modelFamily (default: gpt-5-mini)
• lmToolsBridge.chat.maxIterations (default: 6)
• lmToolsBridge.tools.enabled (default: the list above)
• lmToolsBridge.tools.blacklist (default: empty; comma-separated substrings, case-insensitive)
• lmToolsBridge.tools.schemaDefaults (default: { "maxResults": 1000 }; map of property names to default values injected when absent in tool schemas)

Configure exposed tools

• Right-click the status bar item and select LM Tools Bridge: Configure Tools.
• Use the multi-select list to enable tools. Click Reset to restore defaults.
• Tools matching the blacklist are hidden from the picker and are always disabled.

Help and reload

• The status menu includes Help (opens the GitHub README).
• Reload Window triggers Developer: Reload Window to refresh the extension quickly.

Take over MCP server

When multiple VS Code instances are open, use LM Tools Bridge: Take Over Server to stop the existing MCP server on the port and start it in the current instance.

Status bar indicator

The status bar shows the ownership state:

• LM Tools Bridge: Owner (this instance hosts the port)
• LM Tools Bridge: Non-owner (another instance hosts the port)
• LM Tools Bridge: Off (no server running)

The tooltip includes the owner workspace path(s) and the MCP URL. Click the status bar item to take over when not owning the port.

Logs

Check Output -> LM Tools Bridge for MCP server logs.

Consent notes

Language Model API usage may still trigger VS Code consent prompts or tool confirmations, depending on the selected model and tool implementations.

Development

• Build once: npm run compile
• Watch mode: npm run watch

Notes

• Requires a VS Code version that exposes the vscode.lm API (see package.json engines).