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Title: fix(mcp): don't blank the MCP tools page when tool discovery fails by waleedlatif1 · Pull Request #5816 · simstudioai/sim · GitHub

Open Graph Title: fix(mcp): don't blank the MCP tools page when tool discovery fails by waleedlatif1 · Pull Request #5816 · simstudioai/sim

X Title: fix(mcp): don't blank the MCP tools page when tool discovery fails by waleedlatif1 · Pull Request #5816 · simstudioai/sim

Description: 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)

Open Graph Description: 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 ever...

X Description: 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 ever...

Opengraph URL: https://github.com/simstudioai/sim/pull/5816

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73e287d fix(mcp): don't blank the MCP tools page when tool discovery fails waleedlatif1 Jul 21, 2026 https://github.com/simstudioai/sim/pull/5816/commits/73e287d0c7f8f30375f62456dc4d3e461c32497a
8ad1c31 fix(mcp): surface partial discovery failures per-row and in the notice waleedlatif1 Jul 21, 2026 https://github.com/simstudioai/sim/pull/5816/commits/8ad1c31f22d27649af73ecc72624b94629b91e1c
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