diff --git a/pkg/providers/anthropic/provider.go b/pkg/providers/anthropic/provider.go
index 242ded175..87beae99a 100644
--- a/pkg/providers/anthropic/provider.go
+++ b/pkg/providers/anthropic/provider.go
@@ -351,10 +351,18 @@ func parseResponse(resp *anthropic.Message) *LLMResponse {
 				log.Printf("anthropic: failed to decode tool call input for %q: %v", tu.Name, err)
 				args = map[string]any{"raw": string(tu.Input)}
 			}
+			argsJSON, _ := json.Marshal(args)
 			toolCalls = append(toolCalls, ToolCall{
 				ID:        tu.ID,
 				Name:      tu.Name,
 				Arguments: args,
+				// Function must be populated so Name and Arguments survive
+				// JSON serialization to session storage (both fields are
+				// json:"-" on ToolCall; Function carries them through).
+				Function: &FunctionCall{
+					Name:      tu.Name,
+					Arguments: string(argsJSON),
+				},
 			})
 		}
 	}
diff --git a/pkg/providers/codex_provider.go b/pkg/providers/codex_provider.go
index cf5c2d876..a88535ded 100644
--- a/pkg/providers/codex_provider.go
+++ b/pkg/providers/codex_provider.go
@@ -378,10 +378,18 @@ func parseCodexResponse(resp *responses.Response) *LLMResponse {
 			if err := json.Unmarshal([]byte(item.Arguments), &args); err != nil {
 				args = map[string]any{"raw": item.Arguments}
 			}
+			argsJSON, _ := json.Marshal(args)
 			toolCalls = append(toolCalls, ToolCall{
 				ID:        item.CallID,
 				Name:      item.Name,
 				Arguments: args,
+				// Function must be populated so Name and Arguments survive
+				// JSON serialization to session storage (both fields are
+				// json:"-" on ToolCall; Function carries them through).
+				Function: &FunctionCall{
+					Name:      item.Name,
+					Arguments: string(argsJSON),
+				},
 			})
 		}
 	}
diff --git a/pkg/providers/common/common.go b/pkg/providers/common/common.go
index 23680a1bf..04b011cb0 100644
--- a/pkg/providers/common/common.go
+++ b/pkg/providers/common/common.go
@@ -190,11 +190,19 @@ func ParseResponse(body io.Reader) (*LLMResponse, error) {
 			arguments = DecodeToolCallArguments(tc.Function.Arguments, name)
 		}
 
+		argsJSON, _ := json.Marshal(arguments)
 		toolCall := ToolCall{
 			ID:               tc.ID,
 			Name:             name,
 			Arguments:        arguments,
 			ThoughtSignature: thoughtSignature,
+			// Function must be populated so Name and Arguments survive
+			// JSON serialization to session storage (both fields are
+			// json:"-" on ToolCall; Function carries them through).
+			Function: &FunctionCall{
+				Name:      name,
+				Arguments: string(argsJSON),
+			},
 		}
 
 		if thoughtSignature != "" {