diff --git a/packages/opencode/src/tool/session.ts b/packages/opencode/src/tool/session.ts
index 84369ed20..cd5981681 100644
--- a/packages/opencode/src/tool/session.ts
+++ b/packages/opencode/src/tool/session.ts
@@ -214,7 +214,7 @@ const createOperation = z.strictObject({
     .min(1)
     .optional()
     .describe(
-      "Reuse a standing per-theme child: if a peer child already carries this topic, RELAY the task into it (enqueue+wake) instead of spawning; otherwise create a new child tagged with this topic. Avoids over-spawning sessions for the same theme.",
+      "Semantic key for session reuse: if a peer child already carries this exact topic, RELAY the task into it (enqueue+wake) instead of spawning a new child. When absent, a fresh session is always created — no auto-derivation or guessing. Use the same stable topic string across calls to consolidate same-theme work into one standing child.",
     ),
 })