feat(mcp): implement telemetry middleware

Author: Shanyu-Dabbiru

apps/sim/lib/mcp/resilience/telemetry.ts

@@ -0,0 +1,56 @@
+import { createLogger } from '@sim/logger'
+import type { McpExecutionContext, McpMiddleware, McpMiddlewareNext } from './types'
+import type { McpToolResult } from '@/lib/mcp/types'
+
+const logger = createLogger('mcp:telemetry')
+
+export class TelemetryMiddleware implements McpMiddleware {
+    async execute(
+        context: McpExecutionContext,
+        next: McpMiddlewareNext
+    ): Promise<McpToolResult> {
+        const startTime = performance.now()
+
+        try {
+            const result = await next(context)
+
+            const latency_ms = Math.round(performance.now() - startTime)
+            const isError = result.isError === true
+
+            logger.info('MCP Tool Execution Completed', {
+                toolName: context.toolCall.name,
+                serverId: context.serverId,
+                workspaceId: context.workspaceId,
+                latency_ms,
+                success: !isError,
+                ...(isError && { failure_reason: 'TOOL_ERROR' })
+            })
+
+            return result
+        } catch (error) {
+            const latency_ms = Math.round(performance.now() - startTime)
+
+            // Attempt to determine failure reason based on error
+            let failure_reason = 'API_500' // General failure fallback
+            if (error instanceof Error) {
+                const lowerMsg = error.message.toLowerCase()
+                if (error.name === 'TimeoutError' || lowerMsg.includes('timeout')) {
+                    failure_reason = 'TIMEOUT'
+                } else if (lowerMsg.includes('validation') || error.name === 'ZodError') {
+                    failure_reason = 'VALIDATION_ERROR'
+                }
+            }
+
+            logger.error('MCP Tool Execution Failed', {
+                toolName: context.toolCall.name,
+                serverId: context.serverId,
+                workspaceId: context.workspaceId,
+                latency_ms,
+                failure_reason,
+                err: error instanceof Error ? error.message : String(error)
+            })
+
+            throw error // Re-throw to allow upstream handling (e.g. circuit breaker)
+        }
+    }
+}