diff --git a/codex-rs/core/src/tools/handlers/multi_agents_v2/close_agent.rs b/codex-rs/core/src/tools/handlers/multi_agents_v2/close_agent.rs
index 2fe704823..2296ae5dd 100644
--- a/codex-rs/core/src/tools/handlers/multi_agents_v2/close_agent.rs
+++ b/codex-rs/core/src/tools/handlers/multi_agents_v2/close_agent.rs
@@ -106,6 +106,7 @@ impl ToolHandler for Handler {
 }
 
 #[derive(Debug, Deserialize)]
+#[serde(deny_unknown_fields)]
 struct CloseAgentArgs {
     target: String,
 }
diff --git a/codex-rs/core/src/tools/handlers/multi_agents_v2/list_agents.rs b/codex-rs/core/src/tools/handlers/multi_agents_v2/list_agents.rs
index e18547db9..b3b3f7160 100644
--- a/codex-rs/core/src/tools/handlers/multi_agents_v2/list_agents.rs
+++ b/codex-rs/core/src/tools/handlers/multi_agents_v2/list_agents.rs
@@ -40,6 +40,7 @@ impl ToolHandler for Handler {
 }
 
 #[derive(Debug, Deserialize)]
+#[serde(deny_unknown_fields)]
 struct ListAgentsArgs {
     path_prefix: Option<String>,
 }
diff --git a/codex-rs/core/src/tools/handlers/multi_agents_v2/wait.rs b/codex-rs/core/src/tools/handlers/multi_agents_v2/wait.rs
index 2eb92842f..bf3ad8e93 100644
--- a/codex-rs/core/src/tools/handlers/multi_agents_v2/wait.rs
+++ b/codex-rs/core/src/tools/handlers/multi_agents_v2/wait.rs
@@ -75,6 +75,7 @@ impl ToolHandler for Handler {
 }
 
 #[derive(Debug, Deserialize)]
+#[serde(deny_unknown_fields)]
 struct WaitArgs {
     timeout_ms: Option<i64>,
 }