DEFINITION
Hot Module Reload (HMR) for MCP
Hot Module Reload Protocol Implementation for Model Context Protocol
Definition
A development technique that reloads MCP tool definitions and UI without hard-refreshing the server or canceling the active MCP session. Implemented using MCP protocol primitives: when a tool changes, the server sends a notifications/tools/list_changed notification to the client, which reloads tools. UI changes propagate via Vite HMR.
Examples in the Wild
- Example 1:Modify an MCP tool's schema and see it update in the inspector chat without restarting
- Example 2:Change the UI element returned by an MCP tool and observe the change live in the embedded chat