diff --git a/crates/language_models/src/provider/mistral.rs b/crates/language_models/src/provider/mistral.rs
index e739ccd99d..87c23e49e7 100644
--- a/crates/language_models/src/provider/mistral.rs
+++ b/crates/language_models/src/provider/mistral.rs
@@ -444,6 +444,35 @@ pub fn into_mistral(
         }
     }
 
+    // The Mistral API requires that tool messages be followed by assistant messages,
+    // not user messages. When we have a tool->user sequence in the conversation,
+    // we need to insert a placeholder assistant message to maintain proper conversation
+    // flow and prevent API errors. This is a Mistral-specific requirement that differs
+    // from other language model APIs.
+    let messages = {
+        let mut fixed_messages = Vec::with_capacity(messages.len());
+        let mut messages_iter = messages.into_iter().peekable();
+
+        while let Some(message) = messages_iter.next() {
+            let is_tool_message = matches!(message, mistral::RequestMessage::Tool { .. });
+            fixed_messages.push(message);
+
+            // Insert assistant message between tool and user messages
+            if is_tool_message {
+                if let Some(next_msg) = messages_iter.peek() {
+                    if matches!(next_msg, mistral::RequestMessage::User { .. }) {
+                        fixed_messages.push(mistral::RequestMessage::Assistant {
+                            content: Some(" ".to_string()),
+                            tool_calls: Vec::new(),
+                        });
+                    }
+                }
+            }
+        }
+
+        fixed_messages
+    };
+
     mistral::Request {
         model,
         messages,