The latest updates on your projects. Learn more about Vercel for GitHub.

1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Skipped		May 22, 2026 5:17am

PR Summary

Medium Risk
Changes MCP discovery caching/querying semantics and error handling, which can affect tool availability and refresh behavior across the UI and API. Risk is moderated by targeted cache keys, explicit force-refresh paths, and expanded tests around negative caching.

Overview
MCP tool discovery is now per-server throughout the stack: the UI switches from a single workspace-level tools query to parallel per-server React Query entries (mcpKeys.serverToolsList), and invalidations (OAuth callback, SSE tools_changed, refresh/update/delete) are updated to target the affected server key or the workspace aggregate.

Adds a short TTL “cooldown” negative cache for failing servers in McpService, so repeated discoveries skip recently-failed servers instead of re-paying timeouts; explicit refresh paths pass forceRefresh=true to bypass both positive and negative caches, and new tests cover the updated failure/skip semantics. Also reduces LIST_TOOLS_TIMEOUT_MS (30s→10s) and maps cooldown errors to HTTP 503.

Includes small icon fixes: unique gradient ids for FindymailIcon, updated HubspotIcon path, and adjusted ResendIcon viewBox sizing.

^{Reviewed by Cursor Bugbot for commit ed1b970. Configure here.}

Greptile Summary

This PR refactors MCP tool discovery from a single workspace-aggregated query into N parallel per-server React Query entries (mcpKeys.serverToolsList(workspaceId, serverId)), and adds a server-side negative cache so a failed server is skipped for a short cooldown window instead of re-paying the timeout on every discovery call.

• Per-server useQueries fan-out replaces the single workspace useQuery; the public shape (data, isLoading, isFetching, error) is preserved so existing consumers compile unchanged. The servers-loading state is folded into the aggregate isLoading to prevent the false "loaded, no tools" flash that was flagged in a prior review.
• discoverServerTools adds request-level inflight deduplication, cache-aside logic, and a forceRefresh flag used by the refresh button and OAuth callback paths; the DiscoveryOutcome.error variant now carries originalError: unknown so instanceof exemptions (OAuth, Unauthorized) survive the error-to-string round-trip.
• A negative cache with a 120 s TTL is written on discovery failure and cleared on success; the LIST_TOOLS_TIMEOUT_MS cap is dropped from 30 s to 10 s to shorten worst-case first-failure time.

Confidence Score: 5/5

Safe to merge — the per-server fan-out, negative cache, and forceRefresh bypass all behave as intended and the previous review's concerns have been fully addressed.

The architectural refactor is sound: per-server React Query keys eliminate cross-server blocking, the negative cache is correctly exempted for OAuth errors, and originalError is now threaded through so instanceof checks survive the error-to-outcome round-trip. Tests cover the new cache paths. The only notable discrepancy is between the documented 30 s cooldown in the PR description and the 120 s value in the code — a minor factual mismatch that does not affect runtime correctness since the explicit refresh button bypasses the cache entirely.

No files require special attention. The TTL constant in apps/sim/lib/mcp/utils.ts is worth a second glance to confirm 120 s (vs the PR description's 30s) is intentional.

Important Files Changed

Sequence Diagram

sequenceDiagram
    participant UI as React UI
    participant RQ as React Query
    participant API as /api/mcp/tools/discover
    participant SVC as McpService
    participant Cache as Cache Adapter

    UI->>RQ: useMcpToolsQuery(workspaceId)
    RQ->>API: "GET ?workspaceId&serverId (per server)"
    API->>SVC: discoverServerTools(userId, serverId, ws, false)
    SVC->>Cache: get(serverCacheKey)
    alt Cache hit
        Cache-->>SVC: tools[]
        SVC-->>API: tools[]
    else Negative cache hit
        Cache-->>SVC: failure sentinel
        SVC-->>API: throw McpConnectionError (cooldown)
        API-->>RQ: 503
        RQ-->>UI: error state (server skipped)
    else Cache miss
        SVC->>SVC: listTools() via transport
        alt Success
            SVC->>Cache: set(serverCacheKey, tools, TTL)
            SVC->>Cache: delete(failureCacheKey)
            SVC-->>API: tools[]
            API-->>RQ: 200 tools
            RQ-->>UI: data (merged across servers)
        else Failure
            SVC->>Cache: delete(serverCacheKey)
            SVC->>Cache: set(failureCacheKey, sentinel, FAILURE_TTL)
            SVC-->>API: throw error
            API-->>RQ: 4xx/5xx
            RQ-->>UI: per-server error (other servers still render)
        end
    end

    Note over UI,Cache: Force-refresh path (refresh button / OAuth callback)
    UI->>RQ: useForceRefreshMcpTools.mutate(workspaceId)
    RQ->>API: "GET ?workspaceId&serverId&refresh=true (per server)"
    API->>SVC: discoverServerTools(userId, serverId, ws, true)
    SVC->>SVC: skip both caches, listTools()
    SVC->>Cache: clear failureCacheKey on success
    SVC-->>RQ: fresh tools[]

_{Reviews (4): Last reviewed commit: "fix(mcp): third-round bugbot review" | Re-trigger Greptile}

@greptile

@cursor review

@greptile

@cursor review

@greptile

@cursor review