diff --git a/crates/erp-ai/src/dto/mod.rs b/crates/erp-ai/src/dto/mod.rs
index 72eee09..74a0d48 100644
--- a/crates/erp-ai/src/dto/mod.rs
+++ b/crates/erp-ai/src/dto/mod.rs
@@ -104,6 +104,51 @@ pub enum AnalysisSseEvent {
     Error { message: String },
 }
 
+// === Agent Function Calling DTO ===
+
+/// Agent 对话消息
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ChatMessage {
+    pub role: ChatMessageRole,
+    pub content: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub tool_calls: Option<Vec<ToolCall>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub tool_call_id: Option<String>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum ChatMessageRole {
+    User,
+    Assistant,
+    Tool,
+}
+
+/// Tool 定义（传给 LLM 的 Function Schema）
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ToolDefinition {
+    pub name: String,
+    pub description: String,
+    pub parameters: serde_json::Value,
+}
+
+/// LLM 返回的 Tool Call
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ToolCall {
+    pub id: String,
+    pub name: String,
+    pub arguments: serde_json::Value,
+}
+
+/// Agent 专用生成响应
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct AgentGenerateResponse {
+    pub content: Option<String>,
+    pub tool_calls: Option<Vec<ToolCall>>,
+    pub usage: Option<TokenUsage>,
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;