diff --git a/src/channels/mod.rs b/src/channels/mod.rs
index 31a2b3f..936a26b 100644
--- a/src/channels/mod.rs
+++ b/src/channels/mod.rs
@@ -318,7 +318,12 @@ pub fn build_system_prompt(
         for (name, desc) in tools {
             let _ = writeln!(prompt, "- **{name}**: {desc}");
         }
-        prompt.push('\n');
+        prompt.push_str("\n## Tool Use Protocol\n\n");
+        prompt.push_str("To use a tool, wrap a JSON object in <invoke> tags:\n\n");
+        prompt.push_str("```\n<invoke>\n{\"name\": \"tool_name\", \"arguments\": {\"param\": \"value\"}}\n</invoke>\n```\n\n");
+        prompt.push_str("You may use multiple tool calls in a single response. ");
+        prompt.push_str("After tool execution, results appear in <tool_result> tags. ");
+        prompt.push_str("Continue reasoning with the results until you can give a final answer.\n\n");
     }
 
     // ── 2. Safety ───────────────────────────────────────────────