diff --git a/apps/api/src/api/tool/tool_instances.py b/apps/api/src/api/tool/tool_instances.py
index 255e914..f82803e 100644
--- a/apps/api/src/api/tool/tool_instances.py
+++ b/apps/api/src/api/tool/tool_instances.py
@@ -92,6 +92,7 @@ from src.services.tool.instance_service import (
     expand_glob_source,
     modify_compose_file,
     normalize_git_mount,
+    prepare_manifest_instance,
     pull_repository_updates,
     resolve_git_mount_mappings,
     resolve_git_mounts,
@@ -104,6 +105,8 @@ from src.services.tool.instance_service import (
 logger = logging.getLogger(__name__)
 _event_bus = InstanceEventBus()
 
+router = APIRouter(prefix="/projects", tags=["tool-instances"])
+
 
 @router.post(
     "/{project_id}/repositories/{repo_id}/instances",
@@ -257,6 +260,11 @@ async def create_instance(
                 ssh_key_path = os.path.join(ssh_dir, "id_ed25519")
 
                 # Clone repository
+                if not repo.remote_url:
+                    raise HTTPException(
+                        status_code=status.HTTP_400_BAD_REQUEST,
+                        detail="Repository has no remote URL configured",
+                    )
                 clone_path = clone_repository(
                     remote_url=repo.remote_url,
                     ssh_key_path=ssh_key_path,
@@ -298,16 +306,16 @@ async def create_instance(
         # Create new local branch if requested
         if data.clone_mode == "clone" and data.new_branch:
             try:
-                result = subprocess.run(
+                git_result = subprocess.run(
                     ["git", "-C", repo_path, "checkout", "-b", data.new_branch],
                     capture_output=True,
                     text=True,
                 )
-                if result.returncode != 0:
+                if git_result.returncode != 0:
                     logger.error(
-                        "Failed to create branch %s: %s", data.new_branch, result.stderr
+                        "Failed to create branch %s: %s", data.new_branch, git_result.stderr
                     )
-                    raise RuntimeError(f"Failed to create branch: {result.stderr}")
+                    raise RuntimeError(f"Failed to create branch: {git_result.stderr}")
                 logger.debug(
                     "Created local branch %s in cloned repository", data.new_branch
                 )
@@ -421,6 +429,11 @@ services:
                 "USER_ID": str(user_id),
                 "PROJECT_ID": str(project_id),
             }
+            if not tool_type.compose_template:
+                raise HTTPException(
+                    status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+                    detail="Tool type has no compose template configured",
+                )
             compose_content = render_compose_template(
                 tool_type.compose_template, variables
             )
@@ -1912,9 +1925,10 @@ async def check_instance_tunnel_health(
 
     # If container is not running, override error message
     if not container_healthy:
-        response["error"] = f"Container is {container_info['status']}"
+        error_msg = f"Container is {container_info['status']}"
         if container_info["exit_code"] is not None:
-            response["error"] += f" (exit code: {container_info['exit_code']})"
+            error_msg += f" (exit code: {container_info['exit_code']})"
+        response["error"] = error_msg
 
     return response
 
diff --git a/apps/api/src/services/tool/instance_service.py b/apps/api/src/services/tool/instance_service.py
index bfb8ab4..c2bf3ac 100644
--- a/apps/api/src/services/tool/instance_service.py
+++ b/apps/api/src/services/tool/instance_service.py
@@ -71,6 +71,7 @@ from src.auth.dependencies import _get_owned_project, _get_user
 logger = logging.getLogger(__name__)
 _event_bus = InstanceEventBus()
 
+
 async def resolve_git_mounts(
     session: AsyncSession,
     resolved: ResolvedProfile,
@@ -399,9 +400,6 @@ def expand_glob_source(source_path: str, repo_path: str) -> list[str]:
     return results
 
 
-router = APIRouter(prefix="/projects", tags=["tool-instances"])
-
-
 async def validate_config_profile(
     session: AsyncSession,
     profile_id: str | None,
@@ -741,7 +739,6 @@ def ensure_backend_network_in_compose(compose_path: str) -> None:
         logger.info("Injected backend network '%s' into compose file", network_name)
 
 
-
 async def prepare_manifest_instance(
     session: AsyncSession,
     instance: ToolInstance,
@@ -882,5 +879,3 @@ async def prepare_manifest_instance(
 
     home_dir = get_manifest_home_dir(manifest)
     return image_tag, compose_content, manifest, home_dir
-
-