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MCPJam Inspector gives you full visibility into every exchange between the inspector and your MCP server, across the Playground, Tools, Prompts, and Resources tabs.

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JSON-RPC logging

Every tab that talks to a connected server renders a live JSON-RPC logger. Each entry records the direction (client → server or server → client), the method name, a timestamp, and the full request/response payload. Click an entry to expand and inspect. See Playground → JSON-RPC Logger and MCP Inspector for how it surfaces in each tab.

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Widget debugging

When using ChatGPT Apps or MCP Apps in the Playground, you can debug widget state and globals directly from tool call results.

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Debugging in the chat

Click on any tool call in the chat to expand its debug panel. For widgets, you’ll see three tabs:
  • Data - The tool’s input arguments and output result
  • Widget State - The current state persisted by the widget (updated in real-time as the widget calls setWidgetState)
  • Globals - Environment information passed to the widget including theme, display mode, locale, and device capabilities
A “Click to debug” hint appears on tool calls that have widget debug information available.

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Debugging in the Tools tab

When testing OpenAI Apps or MCP Apps from the Tools tab, the results panel includes a State/Globals button alongside the Component and Raw JSON views. This shows the same widget state and globals information in a dedicated panel.
Widget state persists across follow-up turns in a conversation. Keep state under 4k tokens for optimal performance.