ComfyUI MCP Server

Instructions

Implementation Reference

• comfy_mcp/mcp/server.py:419-491 (handler)

  MCP tool handler for 'generate_from_template'. Validates template and parameters, generates DSL workflow using TemplateManager, handles optional file saving, and returns result with status and content.
  @mcp.tool def generate_from_template( template_name: str, parameters: dict = None, save_path: str = None ) -> dict: """Generate a workflow from a template with custom parameters. Creates a complete DSL workflow by substituting parameters into the template. Optionally saves to file. Args: template_name: Name of the template to use parameters: Dictionary of parameter values to substitute save_path: Optional path to save the generated workflow Returns: Generated DSL content and validation results Examples: generate_from_template("text2img_basic", {"prompt": "sunset"}) generate_from_template("img2img", {"image_path": "input.png"}, "workflows/my_img2img.dsl") """ try: # Validate template exists template = template_manager.get_template(template_name) if template is None: raise ToolError(f"Template '{template_name}' not found") # Validate parameters if provided if parameters: validation = template_manager.validate_parameters(template_name, parameters) if not validation["valid"]: return { "status": "error", "errors": validation["errors"], "warnings": validation.get("warnings", []) } # Generate the workflow dsl_content = template_manager.generate_workflow(template_name, parameters) if dsl_content is None: raise ToolError(f"Failed to generate workflow from template '{template_name}'") result = { "status": "success", "template_name": template_name, "dsl_content": dsl_content, "parameters_used": parameters or {}, "warnings": [] } # Add warnings if any if parameters: validation = template_manager.validate_parameters(template_name, parameters) result["warnings"] = validation.get("warnings", []) # Save to file if requested if save_path: try: path = validate_path(save_path) path.write_text(dsl_content) result["saved_to"] = str(path) result["file_size"] = path.stat().st_size except Exception as e: result["warnings"].append(f"Failed to save to {save_path}: {e}") return result except Exception as e: raise ToolError(f"Error generating from template: {e}")
• comfy_mcp/templates/manager.py:118-162 (helper)

  Core helper method in TemplateManager that resolves the template, merges default and provided parameters, and performs string substitution of parameters into the DSL template content to generate the final workflow.
  def generate_workflow( self, template_name: str, parameters: Optional[Dict[str, str]] = None, source: str = "auto" ) -> Optional[str]: """Generate a workflow DSL from template with parameter substitution.""" # Try custom templates first, then official template = None dsl_content = None if source in ["auto", "custom"]: template = self.custom_templates.get(template_name) if template: dsl_content = template.dsl_content if not template and source in ["auto", "official"]: official_template = official_manager.get_template(template_name) if official_template and official_template.dsl_content: dsl_content = official_template.dsl_content # Create a minimal template-like object for parameter handling template = type('Template', (), { 'parameters': {}, # Official templates don't have default parameters 'dsl_content': dsl_content })() if not template or not dsl_content: return None # Start with template's default parameters final_params = template.parameters.copy() if hasattr(template, 'parameters') and template.parameters else {} # Override with provided parameters if parameters: final_params.update(parameters) # Substitute parameters in DSL content if any if final_params: for param_name, param_value in final_params.items(): # Replace {param_name} with actual value placeholder = f"{{{param_name}}}" dsl_content = dsl_content.replace(placeholder, str(param_value)) return dsl_content
• comfy_mcp/templates/manager.py:163-220 (helper)

  Helper method in TemplateManager that validates provided parameters against template requirements, checks for missing/extra params, and validates types/constraints for specific parameters like width, steps, cfg.
  def validate_parameters( self, template_name: str, parameters: Dict[str, str], source: str = "auto" ) -> Dict[str, List[str]]: """Validate parameters for a template.""" # Try to find template in custom or official template = None if source in ["auto", "custom"]: template = self.custom_templates.get(template_name) if not template and source in ["auto", "official"]: official_template = official_manager.get_template(template_name) if official_template and official_template.dsl_content: # Create minimal template object for validation template = type('Template', (), { 'parameters': {}, 'dsl_content': official_template.dsl_content })() if not template: return { "valid": False, "errors": [f"Template '{template_name}' not found"], "warnings": [] } errors = [] warnings = [] # Check for required parameters (those in template but not provided) template_params = template.parameters or {} required_params = set(self._extract_parameters_from_dsl(template.dsl_content)) provided_params = set(parameters.keys()) missing_params = required_params - provided_params if missing_params: errors.append(f"Missing required parameters: {', '.join(missing_params)}") # Check for extra parameters extra_params = provided_params - required_params if extra_params: warnings.append(f"Extra parameters will be ignored: {', '.join(extra_params)}") # Validate specific parameter types/constraints for param_name, param_value in parameters.items(): if param_name in template_params: validation_errors = self._validate_parameter_value( param_name, param_value, template_name ) errors.extend(validation_errors) return { "valid": len(errors) == 0, "errors": errors, "warnings": warnings }