diff --git a/codex-rs/codex-mcp/src/connection_manager.rs b/codex-rs/codex-mcp/src/connection_manager.rs
index 1a7c2544f3..8144f5b227 100644
--- a/codex-rs/codex-mcp/src/connection_manager.rs
+++ b/codex-rs/codex-mcp/src/connection_manager.rs
@@ -188,7 +188,6 @@ impl McpConnectionManager {
         let cancel_token = CancellationToken::new();
         let mut clients = HashMap::new();
         let mut server_metadata = HashMap::new();
-        let mut preflight_failures = Vec::new();
         let mut join_set = JoinSet::new();
         let elicitation_requests = ElicitationRequestManager::new(
             approval_policy.value(),
@@ -205,16 +204,7 @@ impl McpConnectionManager {
             .into_iter()
             .filter(|(_, server)| server.enabled())
         {
-            let Some(configured_server) = server.configured_config() else {
-                unreachable!("effective MCP servers are configured");
-            };
-            let startup_unavailable_reason =
-                runtime_environment.startup_unavailable_reason(&server_name, configured_server);
-            if let Some(reason) = startup_unavailable_reason.as_deref() {
-                // Treat placement mismatch like a per-server startup failure
-                // so usable MCP servers in the same config can still start.
-                warn!(server = %server_name, "{reason}; skipping MCP server");
-            }
+            server_metadata.insert(server_name.clone(), McpServerMetadata::from(&server));
             let cancel_token = cancel_token.child_token();
             let _ = emit_update(
                 startup_submit_id.as_str(),
@@ -225,31 +215,6 @@ impl McpConnectionManager {
                 },
             )
             .await;
-            if let Some(reason) = startup_unavailable_reason {
-                let auth_entry = auth_entries.get(&server_name).cloned();
-                let error = mcp_init_error_display(
-                    server_name.as_str(),
-                    auth_entry.as_ref(),
-                    &StartupOutcomeError::Failed {
-                        error: reason.clone(),
-                    },
-                );
-                let _ = emit_update(
-                    startup_submit_id.as_str(),
-                    &tx_event,
-                    McpStartupUpdateEvent {
-                        server: server_name.clone(),
-                        status: McpStartupStatus::Failed { error },
-                    },
-                )
-                .await;
-                preflight_failures.push(McpStartupFailure {
-                    server: server_name,
-                    error: reason,
-                });
-                continue;
-            }
-            server_metadata.insert(server_name.clone(), McpServerMetadata::from(&server));
             let codex_apps_tools_cache_context = if server_name == CODEX_APPS_MCP_SERVER_NAME {
                 Some(CodexAppsToolsCacheContext {
                     codex_home: codex_home.clone(),
@@ -332,10 +297,7 @@ impl McpConnectionManager {
         };
         tokio::spawn(async move {
             let outcomes = join_set.join_all().await;
-            let mut summary = McpStartupCompleteEvent {
-                failed: preflight_failures,
-                ..Default::default()
-            };
+            let mut summary = McpStartupCompleteEvent::default();
             for (server_name, outcome) in outcomes {
                 match outcome {
                     Ok(_) => summary.ready.push(server_name),
diff --git a/codex-rs/codex-mcp/src/connection_manager_tests.rs b/codex-rs/codex-mcp/src/connection_manager_tests.rs
index 4d3526ad73..c76e7a9e9a 100644
--- a/codex-rs/codex-mcp/src/connection_manager_tests.rs
+++ b/codex-rs/codex-mcp/src/connection_manager_tests.rs
@@ -848,7 +848,7 @@ async fn list_all_tools_adds_server_metadata_to_cached_tools() {
 }
 
 #[tokio::test]
-async fn no_local_runtime_skips_local_stdio_but_keeps_local_http_server() {
+async fn no_local_runtime_fails_local_stdio_but_keeps_local_http_server() {
     let approval_policy = Constrained::allow_any(AskForApproval::OnFailure);
     let (tx_event, rx_event) = async_channel::unbounded();
     drop(rx_event);
@@ -930,7 +930,7 @@ async fn no_local_runtime_skips_local_stdio_but_keeps_local_http_server() {
     )
     .await;
 
-    assert!(!manager.clients.contains_key("stdio"));
+    assert!(manager.clients.contains_key("stdio"));
     assert!(manager.clients.contains_key("http"));
     assert!(
         !manager
@@ -942,6 +942,10 @@ async fn no_local_runtime_skips_local_stdio_but_keeps_local_http_server() {
         .await;
     assert_eq!(failures.len(), 1);
     assert_eq!(failures[0].server, "stdio");
+    assert_eq!(
+        failures[0].error,
+        "local stdio MCP server `stdio` requires a local environment"
+    );
     cancel_token.cancel();
 }
 
diff --git a/codex-rs/codex-mcp/src/rmcp_client.rs b/codex-rs/codex-mcp/src/rmcp_client.rs
index 6420cc8eb8..687576dfac 100644
--- a/codex-rs/codex-mcp/src/rmcp_client.rs
+++ b/codex-rs/codex-mcp/src/rmcp_client.rs
@@ -566,6 +566,9 @@ async fn make_rmcp_client(
     let config = match server.launch() {
         McpServerLaunch::Configured(config) => config.as_ref().clone(),
     };
+    if let Some(reason) = runtime_environment.startup_unavailable_reason(server_name, &config) {
+        return Err(StartupOutcomeError::from(anyhow!(reason)));
+    }
     let McpServerConfig {
         transport,
         experimental_environment,