Summary

The Resources panel can render the wrong resource payload after switching between already-read resources.

In my local repro, resources/list returns three distinct resources, and raw resources/read returns three distinct payloads, but Inspector's detail pane can show the payload for a different resource than the one currently selected.

Environment

• MCP Inspector: v0.21.2
• Container image in use locally: ghcr.io/modelcontextprotocol/inspector:latest
• Image labels: 0.21.2-hotfix-3, revision adfcccca529088099d41d08459f55214bfb9b874
• Transport: Streamable HTTP
• Connection type: Direct

Repro

1. Connect to an MCP server that supports resources/list and resources/read.
2. List resources.
3. Click resource A and let Inspector read/display it.
4. Click resource B and let Inspector read/display it.
5. Click resource A again.

Expected

The detail pane should display resource A's payload again.

Actual

The detail pane can continue showing resource B's payload, even though the selected item and heading indicate resource A.

I also saw this related symptom:

• clicking Build a Report approved tools showed a detail payload whose uri field was mcp://benefitsolver/report/context-md

Server-side validation

I verified the server responses independently with raw JSON-RPC calls:

• resources/list returns distinct resources
• resources/read returns distinct payloads for each URI

So this appears to be a client-side Inspector state/rendering bug, not a server bug.

Likely cause

I traced this locally and found two issues in the client:

1. The Resources tab renders a single global resourceContent string instead of the content for selectedResource.uri.
2. readResource() short-circuits if a URI is already cached, so re-selecting a cached resource does not repopulate the visible pane.

That combination leaves the detail pane showing stale content from the last-read resource.

Suggested fix

• Derive displayed content from resourceContentMap[selectedResource.uri]
• Keep Refresh as a real refresh by bypassing the cache check when explicitly requested