diff --git a/src/api/completions.rs b/src/api/completions.rs
index 0e09b47..c2924bf 100644
--- a/src/api/completions.rs
+++ b/src/api/completions.rs
@@ -18,20 +18,26 @@ use super::AppState;
 // ─── Input extraction ────────────────────────────────────────────────────────
 
 /// Extract user text from Chat Completions messages array.
+///
+/// When tool results are present, builds the full conversation including
+/// tool call results so the model can continue after tool use.
 fn extract_chat_input(messages: &[CompletionMessage]) -> String {
+    let has_tool_results = messages.iter().any(|m| m.role == "tool");
+
+    if has_tool_results {
+        // Build full conversation context including tool results
+        return build_conversation_with_tools(messages);
+    }
+
+    // Simple path: no tools, just extract system + last user message
     let mut system_parts = Vec::new();
     let mut user_parts = Vec::new();
 
     for msg in messages {
-        let text = match &msg.content {
-            serde_json::Value::String(s) => s.clone(),
-            serde_json::Value::Array(arr) => arr
-                .iter()
-                .filter_map(|item| item["text"].as_str())
-                .collect::<Vec<_>>()
-                .join("\n"),
-            _ => continue,
-        };
+        let text = extract_message_text(&msg.content);
+        if text.is_empty() {
+            continue;
+        }
         match msg.role.as_str() {
             "system" | "developer" => system_parts.push(text),
             "user" => user_parts.push(text),
@@ -44,13 +50,87 @@ fn extract_chat_input(messages: &[CompletionMessage]) -> String {
         result.push_str(&system_parts.join("\n"));
         result.push_str("\n\n");
     }
-    // Use the last user message
     if let Some(last) = user_parts.last() {
         result.push_str(last);
     }
     result.trim().to_string()
 }
 
+/// Extract text content from a message's content field (string or array).
+fn extract_message_text(content: &serde_json::Value) -> String {
+    match content {
+        serde_json::Value::String(s) => s.clone(),
+        serde_json::Value::Array(arr) => arr
+            .iter()
+            .filter_map(|item| item["text"].as_str())
+            .collect::<Vec<_>>()
+            .join("\n"),
+        _ => String::new(),
+    }
+}
+
+/// Build conversation text that includes tool call results.
+///
+/// Format:
+/// [system prompt]
+/// [user message]
+/// [assistant called tool X with args Y]
+/// [tool result: Z]
+/// [user followup if any]
+fn build_conversation_with_tools(messages: &[CompletionMessage]) -> String {
+    let mut parts = Vec::new();
+
+    for msg in messages {
+        match msg.role.as_str() {
+            "system" | "developer" => {
+                let text = extract_message_text(&msg.content);
+                if !text.is_empty() {
+                    parts.push(text);
+                }
+            }
+            "user" => {
+                let text = extract_message_text(&msg.content);
+                if !text.is_empty() {
+                    parts.push(text);
+                }
+            }
+            "assistant" => {
+                // Include assistant text if any
+                let text = extract_message_text(&msg.content);
+                if !text.is_empty() {
+                    parts.push(text);
+                }
+                // Include tool calls as context
+                if let Some(ref tool_calls) = msg.tool_calls {
+                    for tc in tool_calls {
+                        if let Some(func) = tc.get("function") {
+                            let name = func["name"].as_str().unwrap_or("unknown");
+                            let args = func["arguments"].as_str().unwrap_or("{}");
+                            parts.push(format!(
+                                "[Tool call: {}({})]",
+                                name, args
+                            ));
+                        }
+                    }
+                }
+            }
+            "tool" => {
+                let text = extract_message_text(&msg.content);
+                let tool_id = msg.tool_call_id.as_deref().unwrap_or("unknown");
+                if !text.is_empty() {
+                    parts.push(format!(
+                        "[Tool result ({})]:\n{}",
+                        tool_id, text
+                    ));
+                }
+            }
+            _ => {}
+        }
+    }
+
+    parts.join("\n\n")
+}
+
 // ─── Handler ─────────────────────────────────────────────────────────────────
 
 /// POST /v1/chat/completions — OpenAI Chat Completions API compatibility shim.
diff --git a/src/api/types.rs b/src/api/types.rs
index 87c429f..8bdb016 100644
--- a/src/api/types.rs
+++ b/src/api/types.rs
@@ -58,7 +58,12 @@ pub(crate) struct CompletionRequest {
 #[derive(Deserialize)]
 pub(crate) struct CompletionMessage {
     pub role: String,
+    #[serde(default)]
     pub content: serde_json::Value,
+    /// Tool calls made by the assistant (for assistant messages)
+    pub tool_calls: Option<Vec<serde_json::Value>>,
+    /// Tool call ID this message is responding to (for tool messages)
+    pub tool_call_id: Option<String>,
 }
 
 fn default_timeout() -> u64 {