diff --git a/src/agent/agent_loop.rs b/src/agent/agent_loop.rs
index a6da683..8c08e09 100644
--- a/src/agent/agent_loop.rs
+++ b/src/agent/agent_loop.rs
@@ -125,6 +125,15 @@ fn parse_pending_tool_output(output: &str) -> Option<String> {
     output.strip_prefix(PENDING_USER_ACTION_MARKER).map(|rest| rest.trim().to_string())
 }
 
+fn normalize_tool_arguments(arguments: &serde_json::Value) -> serde_json::Value {
+    match arguments {
+        serde_json::Value::String(raw) => {
+            serde_json::from_str(raw).unwrap_or_else(|_| arguments.clone())
+        }
+        _ => arguments.clone(),
+    }
+}
+
 fn is_recoverable_llm_error(error: &str) -> bool {
     let normalized = error.to_ascii_lowercase();
     normalized.contains("504")
@@ -720,8 +729,10 @@ impl AgentLoop {
 
     /// Internal tool execution without event tracking.
     async fn execute_tool_internal(&self, tool_call: &ToolCall) -> ToolExecutionOutcome {
+        let normalized_arguments = normalize_tool_arguments(&tool_call.arguments);
+
         if tool_call.name == "skill_activate" {
-            let skill_name = match tool_call.arguments.get("name").and_then(|v| v.as_str()) {
+            let skill_name = match normalized_arguments.get("name").and_then(|v| v.as_str()) {
                 Some(name) if !name.trim().is_empty() => name,
                 _ => {
                     self.record_skill_event(
@@ -729,7 +740,7 @@ impl AgentLoop {
                         None,
                         serde_json::json!({
                             "reason": "missing_name",
-                            "arguments": tool_call.arguments,
+                            "arguments": normalized_arguments,
                         }),
                     );
                     return ToolExecutionOutcome::failure(
@@ -752,7 +763,7 @@ impl AgentLoop {
                         Some(skill_name),
                         serde_json::json!({
                             "reason": err,
-                            "arguments": tool_call.arguments,
+                            "arguments": normalized_arguments,
                         }),
                     );
                     ToolExecutionOutcome::failure(
@@ -774,7 +785,7 @@ impl AgentLoop {
             }
         };
 
-        match tool.execute_with_context(&self.tool_context, tool_call.arguments.clone()).await {
+        match tool.execute_with_context(&self.tool_context, normalized_arguments).await {
             Ok(result) => {
                 if result.success {
                     if let Some(pending_output) = parse_pending_tool_output(&result.output) {
@@ -940,6 +951,22 @@ mod tests {
         assert!(parse_pending_tool_output("normal output").is_none());
     }
 
+    #[test]
+    fn test_normalize_tool_arguments_parses_stringified_json() {
+        let normalized = normalize_tool_arguments(&serde_json::Value::String(
+            "{\"command\":\"ls -la\"}".to_string(),
+        ));
+
+        assert_eq!(normalized, serde_json::json!({ "command": "ls -la" }));
+    }
+
+    #[test]
+    fn test_normalize_tool_arguments_keeps_plain_string() {
+        let normalized = normalize_tool_arguments(&serde_json::Value::String("plain text".to_string()));
+
+        assert_eq!(normalized, serde_json::Value::String("plain text".to_string()));
+    }
+
     #[test]
     fn test_build_content_blocks_skips_non_image_media_refs() {
         let temp_dir = tempdir().unwrap();