diff --git a/src/acp/client.test.ts b/src/acp/client.test.ts
index 554823600..7b266b606 100644
--- a/src/acp/client.test.ts
+++ b/src/acp/client.test.ts
@@ -85,6 +85,18 @@ describe("resolvePermissionRequest", () => {
     expect(res).toEqual({ outcome: { outcome: "selected", optionId: "reject" } });
   });
 
+  it("prompts when tool name contains read/search substrings but isn't a safe kind", async () => {
+    const prompt = vi.fn(async () => false);
+    const res = await resolvePermissionRequest(
+      makePermissionRequest({
+        toolCall: { toolCallId: "tool-t", title: "thread: reply", status: "pending" },
+      }),
+      { prompt, log: () => {} },
+    );
+    expect(prompt).toHaveBeenCalledTimes(1);
+    expect(res).toEqual({ outcome: { outcome: "selected", optionId: "reject" } });
+  });
+
   it("uses allow_always and reject_always when once options are absent", async () => {
     const options: RequestPermissionRequest["options"] = [
       { kind: "allow_always", name: "Always allow", optionId: "allow-always" },
diff --git a/src/acp/client.ts b/src/acp/client.ts
index c6ea3ed38..6d35a8089 100644
--- a/src/acp/client.ts
+++ b/src/acp/client.ts
@@ -96,11 +96,17 @@ function resolveToolKindForPermission(
   }
   const normalized = name.toLowerCase();
 
-  // Prefer a conservative classifier: if in doubt, return "other" (prompt-required).
-  if (normalized === "read" || normalized.includes("read")) {
+  const hasToken = (token: string) => {
+    // Tool names tend to be snake_case. Avoid substring heuristics (ex: "thread" contains "read").
+    const re = new RegExp(`(?:^|[._-])${token}(?:$|[._-])`);
+    return re.test(normalized);
+  };
+
+  // Prefer a conservative classifier: only classify safe kinds when confident.
+  if (normalized === "read" || hasToken("read")) {
     return "read";
   }
-  if (normalized === "search" || normalized.includes("search") || normalized.includes("find")) {
+  if (normalized === "search" || hasToken("search") || hasToken("find")) {
     return "search";
   }
   if (normalized.includes("fetch") || normalized.includes("http")) {