diff --git a/src/providers/openai.rs b/src/providers/openai.rs
index 240ea6b1..c7c796e8 100644
--- a/src/providers/openai.rs
+++ b/src/providers/openai.rs
@@ -838,9 +838,11 @@ impl super::Provider for OpenAIProvider {
                                             
                                             // Yield the tool calls in two chunks to mimic standard streaming behavior
                                             // Chunk 1: Initialization (id, name)
-                                            let init_deltas: Vec<crate::models::ToolCallDelta> = embedded_calls.iter().enumerate().map(|(idx, tc)| {
+                                            let init_deltas: Vec<crate::models::ToolCallDelta> = embedded_calls.iter().map(|tc| {
+                                                let tc_idx = next_tool_index;
+                                                next_tool_index += 1;
                                                 crate::models::ToolCallDelta {
-                                                    index: idx as u32,
+                                                    index: tc_idx,
                                                     id: Some(tc.id.clone()),
                                                     call_type: Some("function".to_string()),
                                                     function: Some(crate::models::FunctionCallDelta {
@@ -860,9 +862,13 @@ impl super::Provider for OpenAIProvider {
                                             };
 
                                             // Chunk 2: Payload (arguments)
-                                            let arg_deltas: Vec<crate::models::ToolCallDelta> = embedded_calls.into_iter().enumerate().map(|(idx, tc)| {
+                                            // Reset temp index for payload chunk
+                                            let mut payload_idx = next_tool_index - embedded_calls.len() as u32;
+                                            let arg_deltas: Vec<crate::models::ToolCallDelta> = embedded_calls.into_iter().map(|tc| {
+                                                let tc_idx = payload_idx;
+                                                payload_idx += 1;
                                                 crate::models::ToolCallDelta {
-                                                    index: idx as u32,
+                                                    index: tc_idx,
                                                     id: None,
                                                     call_type: None,
                                                     function: Some(crate::models::FunctionCallDelta {