diff --git a/codex-rs/mcp-server/tests/common/config.rs b/codex-rs/mcp-server/tests/common/config.rs
new file mode 100644
index 0000000000..b147de00ca
--- /dev/null
+++ b/codex-rs/mcp-server/tests/common/config.rs
@@ -0,0 +1,26 @@
+use std::path::Path;
+
+/// Write a minimal Codex config.toml pointing at the provided mock server URI.
+/// Used by tests that don't exercise approval/sandbox variations.
+pub fn create_config_toml(codex_home: &Path, server_uri: &str) -> std::io::Result<()> {
+    let config_toml = codex_home.join("config.toml");
+    std::fs::write(
+        config_toml,
+        format!(
+            r#"
+model = "mock-model"
+approval_policy = "never"
+sandbox_mode = "danger-full-access"
+
+model_provider = "mock_provider"
+
+[model_providers.mock_provider]
+name = "Mock provider for test"
+base_url = "{server_uri}/v1"
+wire_api = "chat"
+request_max_retries = 0
+stream_max_retries = 0
+"#
+        ),
+    )
+}