fix(mcp): don't blank the MCP tools page when tool discovery fails

[waleedlatif1]

Summary

• A tool-discovery failure (one slow/failing server — e.g. a stalled streamable-HTTP transport timing out) replaced the entire MCP tools server list with a centered error banner, hiding every server including healthy/authorizable ones.
• Root cause: const error = toolsError || serversError gated the whole list, conflating a tool-discovery failure with a server-list-load failure. Either one blanked the page.
• Fix: gate the full-list replacement on serversError only (the list genuinely failing to load). When the servers loaded, always render the list — each row already surfaces its own discovery state via toolsStateByServer (per-row status), with a small non-blocking notice above the list when discovery had issues.
• This restores the per-server isolation intent: one bad server can't hide the others, and you can still act on the list (reconnect an OAuth server, retry, etc.).

Type of Change

• Bug fix (UX resilience)

Testing

• Type-checks + biome clean.
• Audited the full discovery lifecycle (hook useMcpToolsQuery per-server useQueries isolation, the discover route, the service single/all-server paths, and every render state): page never blanks on a tool-discovery failure in any of loading / no-servers / servers+toolsError / serversError / detail-view; per-server isolation intact; no other code hides the list; no unused vars or regressions.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Skipped		Jul 21, 2026 8:43pm

[cursor]

PR Summary

Low Risk
Settings UI error-handling only; no auth, API, or data-model changes.

Overview
Fixes MCP settings so a tool-discovery failure no longer replaces the whole server list with a full-page error. Full-page blocking state now uses serversError only; toolsError and per-server failures from toolsStateByServer no longer hide healthy servers.

When the list still loads, users see a non-blocking notice if any discovery failed, and each ServerListItem can show a per-row discoveryError (with error styling) instead of misleading “0 tools” when stored connection status hasn’t caught up yet.

^{Reviewed by Cursor Bugbot for commit 8ad1c31. Configure here.}

[greptile-apps]

Greptile Summary

This PR keeps the MCP server list usable when tool discovery fails. The main changes are:

• Blocks the full page only when the server list fails to load.
• Shows a non-blocking notice for discovery failures.
• Displays live discovery errors on affected server rows.

Confidence Score: 5/5

This looks safe to merge.

• The updated per-server error handling resolves the reported partial-discovery behavior.
• No blocking issues were found in the changed code.

Important Files Changed

Filename	Overview
apps/sim/app/workspace/[workspaceId]/settings/components/mcp/mcp.tsx	Separates server-list errors from tool-discovery errors and surfaces partial failures without hiding the server list.

_{Reviews (2): Last reviewed commit: "fix(mcp): surface partial discovery fail..." | Re-trigger Greptile}

[waleedlatif1]

@greptile

[waleedlatif1]

@cursor review

[cursor]

✅ Bugbot reviewed your changes and found no new issues!

Comment @cursor review or bugbot run to trigger another review on this PR

^{Reviewed by Cursor Bugbot for commit 8ad1c31. Configure here.}