From ee2763e9b20f937de0c2adffff8dddfe2d5af3b3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mikl=C3=B3s=20Fazekas?= <mfazekas@szemafor.com>
Date: Mon, 12 Oct 2026 03:18:11 +0200
Subject: [PATCH] Reject unknown params in t3_thread_read (#17823)

---
 .../src/mcp/OrchestratorMcpToolkit.integration.test.ts      | 6 ++++++
 apps/server/src/mcp/toolkits/orchestrator/tools.ts          | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/apps/server/src/mcp/OrchestratorMcpToolkit.integration.test.ts b/apps/server/src/mcp/OrchestratorMcpToolkit.integration.test.ts
index aeae1a94c68b06ec840653c5d069cc912499cdd0..0b3d1b0e18cf2c1c892fbad8d7d4de2a63e43e55 100644
--- a/apps/server/src/mcp/OrchestratorMcpToolkit.integration.test.ts
+++ b/apps/server/src/mcp/OrchestratorMcpToolkit.integration.test.ts
@@ -1426,6 +1426,12 @@ describe("orchestrator MCP toolkit", () => {
             expect(threadListTool?.tool.annotations?.idempotentHint).toBe(true);
             const threadReadTool = server.tools.find(({ tool }) => tool.name === "t3_thread_read");
             expect(threadReadTool?.tool.annotations?.readOnlyHint).toBe(false);
+            expect(threadReadTool?.tool.inputSchema).toMatchObject({ additionalProperties: false });
+            const unknownPagingParamError = yield* invoke("t3_thread_read", {
+              threadId: parentThreadId,
+              cursor: 90,
+            }).pipe(Effect.flip);
+            expect(unknownPagingParamError.message).toContain("Expected no excess property");
             const threadUpdateTool = server.tools.find(
               ({ tool }) => tool.name === "t3_thread_update",
             );
diff --git a/apps/server/src/mcp/toolkits/orchestrator/tools.ts b/apps/server/src/mcp/toolkits/orchestrator/tools.ts
index 3248618a2de08ffb38803ef0c99ac58122d0518d..f2c34bb22cbe151b496d7ec28a0cf33a68bb8520 100644
--- a/apps/server/src/mcp/toolkits/orchestrator/tools.ts
+++ b/apps/server/src/mcp/toolkits/orchestrator/tools.ts
@@ -214,6 +214,8 @@ const ThreadReadTool = Tool.make("t3_thread_read", {
   dependencies,
 })
   .annotate(Tool.Title, "Read a T3 thread")
+  // Strict so a misspelled paging param fails instead of silently reading from position 0.
+  .annotate(Tool.Strict, true)
   .annotate(Tool.Readonly, false)
   .annotate(Tool.Destructive, false)
   .annotate(Tool.Idempotent, true);
-- 
2.54.0