fix(search): read Search MCP date filters without an offset as UTC (#9798)

A date filter sent without its UTC offset failed validation, and the client
resent the same value with Z appended, costing a full extra round. Accept the
offset-less form and read it as UTC up front. tools/list is unchanged.

Author: waleedlatif1

apps/sim/lib/api/contracts/knowledge/mcp.ts

@@ -19,23 +19,30 @@ export const organizationKnowledgeMcpContract = defineRouteContract({
 
 const LIVE_SEARCH_MCP_DEFAULT_TOP_K = { federated: 30, scoped: 20 } as const
 
+const HAS_UTC_OFFSET = /(Z|[+-]\d{2}:\d{2})$/
+
 /**
- * A datetime field without the regex its JSON Schema would otherwise carry beside
- * `format: "date-time"`. Every tools/list call resends the schema, and parsing still rejects a
- * string that is not an ISO datetime with an offset.
+ * An ISO datetime filter that reads a value without an offset as UTC, which is what a client
+ * resends after that value is rejected, so the call succeeds on the first try. Its JSON Schema
+ * keeps `format: "date-time"` and the field's description but not the regex, which every
+ * tools/list call would resend.
  */
-function withoutPatternInJsonSchema<T extends z.ZodType>(schema: T): T {
-  return schema.meta({ pattern: undefined })
+function mcpDateFilter(field: z.ZodOptional<z.ZodString>) {
+  return z.iso
+    .datetime({ offset: true, local: true })
+    .transform((value) => (HAS_UTC_OFFSET.test(value) ? value : `${value}Z`))
+    .optional()
+    .meta({ pattern: undefined, description: field.description })
 }
 
 const { startDate, endDate, modifiedAfter, modifiedBefore } = workspaceSearchFiltersSchema.shape
 
 /** The date filters of the Search MCP tools, as their tools/list schema presents them. */
 const mcpDateFilterFields = {
-  startDate: withoutPatternInJsonSchema(startDate),
-  endDate: withoutPatternInJsonSchema(endDate),
-  modifiedAfter: withoutPatternInJsonSchema(modifiedAfter),
-  modifiedBefore: withoutPatternInJsonSchema(modifiedBefore),
+  startDate: mcpDateFilter(startDate),
+  endDate: mcpDateFilter(endDate),
+  modifiedAfter: mcpDateFilter(modifiedAfter),
+  modifiedBefore: mcpDateFilter(modifiedBefore),
 }
 
 export const liveSearchMcpSchema = searchWorkspaceInputFieldsSchema

apps/sim/lib/knowledge/mcp/server.protocol.test.ts

@@ -98,6 +98,26 @@ describe('Search MCP protocol', () => {
       expect(read.content).toEqual([
         { type: 'text', text: expect.stringContaining('Read evidence') },
       ])
+      const offsetless = await client.callTool({
+        name: 'search',
+        arguments: {
+          query: 'release',
+          startDate: '2026-09-28T00:00:00',
+          endDate: '2026-10-08T00:00',
+          modifiedAfter: '2026-09-01T08:00:00-07:00',
+        },
+      })
+      expect(offsetless.isError).not.toBe(true)
+      expect(mocks.liveSearch.mock.lastCall?.[0].input.filters).toMatchObject({
+        startDate: '2026-09-28T00:00:00Z',
+        endDate: '2026-10-08T00:00Z',
+        modifiedAfter: '2026-09-01T08:00:00-07:00',
+      })
+      const notADate = await client.callTool({
+        name: 'search',
+        arguments: { query: 'release', startDate: '2026-09-28' },
+      })
+      expect(notADate.isError).toBe(true)
     } finally {
       await client.close()
       await server.close()