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Scaffolder MCP Backend Plugin#

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Overview#

The Scaffolder MCP backend plugin (@terasky/backstage-plugin-scaffolder-mcp-backend) provides Model Context Protocol (MCP) actions for programmatic interaction with Backstage software templates. This enables AI agents and automation tools to discover, inspect, and execute software templates through a standardized interface.

Features#

Template Discovery and Management#

  • List all available software templates
  • Retrieve template metadata and descriptions
  • Access template tags and categorization
  • Get full entity references for templates
  • Retrieve parameter schemas for templates
  • Understand input requirements and validation rules
  • Execute templates with provided parameters
  • Monitor task status and completion

Scaffolder Actions Discovery#

  • List all available scaffolder actions
  • Get detailed action schemas and descriptions
  • Discover action input/output parameters
  • Access action examples and usage patterns
  • Filter actions by ID or description
  • Programmatic action discovery for template development

Template Extensions Discovery#

  • List all available template extensions (filters and functions)
  • Discover Nunjucks filters and global functions
  • Get extension schemas and descriptions
  • Access extension examples and usage patterns
  • Filter extensions by name or type
  • Support for template development and customization

MCP Actions Support#

  • 7 comprehensive MCP actions
  • Standardized MCP action interface
  • Integration with AI agents and automation tools
  • Programmatic access to scaffolder functionality
  • Task polling and status monitoring

Integration#

  • Seamless integration with Backstage scaffolder
  • Authentication and authorization support
  • Permission framework integration
  • Task lifecycle management

Technical Details#

Available MCP Actions#

The plugin provides 7 comprehensive MCP actions grouped into three categories:

Template Management Actions#

  1. list_software_templates

    • Lists all available software templates in the Backstage catalog
    • Returns template metadata including name, title, description, tags, and entity references
    • No input parameters required
    • Useful for template discovery and selection

  2. get_software_template_parameter_schema

    • Retrieves the parameter schema for a specific template
    • Input: Template name or full entity reference
    • Returns JSON Schema describing required and optional input fields
    • Includes validation rules, default values, and field descriptions

  3. run_software_template

    • Executes a software template with provided parameters
    • Input: Template reference and parameters object
    • Polls task status every second until completion (5-minute timeout)
    • Returns task ID, status, and execution outputs (e.g., repository URL, entity reference)

Scaffolder Actions Discovery#

  1. list_software_template_actions

    • Lists all available scaffolder actions that can be used in templates
    • Optional filter parameter to search by ID or description
    • Returns action IDs and descriptions
    • Useful for discovering available actions when building templates

  2. get_software_template_action_details

    • Retrieves detailed information about a specific scaffolder action
    • Input: Action ID (e.g., "fetch:plain", "catalog:register")
    • Returns action schema (input/output), description, and examples
    • Essential for understanding how to use actions in templates

Template Extensions Discovery#

  1. list_software_template_extensions

    • Lists all available template extensions (filters and functions)
    • Optional filter parameter to search by name or description
    • Returns extension names, types (filter/function/value), and descriptions
    • Useful for discovering Nunjucks filters and global functions

  2. get_software_template_extension_details

    • Retrieves detailed information about a specific template extension
    • Input: Extension name (e.g., "parseRepoUrl", "parseEntityRef")
    • Returns extension type, schema, description, and examples
    • Essential for understanding how to use extensions in templates

Integration Points#

  • Backstage Scaffolder Framework
  • Backstage Catalog
  • MCP Actions Registry
  • Backstage Authentication System
  • Backstage Permission Framework

Security Considerations#

  • All actions run on behalf of the authenticated user
  • Leverages Backstage's authentication system
  • Respects scaffolder permissions and policies
  • Secure parameter handling and validation
  • Audit trail through scaffolder task logs

Task Management#

  • Automatic task status polling
  • Configurable timeout (default: 5 minutes)
  • Status tracking (pending, processing, completed, failed, cancelled)
  • Output value retrieval on completion
  • Error handling and reporting