Mendix Studio Pro MCP Extension

A C# extension for Mendix Studio Pro 11.5 that exposes the full modeling API through a Model Context Protocol (MCP) server over HTTP/SSE. Enables AI tools (Claude, Cursor, Copilot, etc.) to read, create, modify, and manage Mendix application models programmatically.

83 tools across domain modeling, microflows, pages, security, workflows, and more.

Mendix Marketplace Module

A pre-built version for Mendix 10.24.2 is available in the .github/Mendix Marketplace Module/ folder with installation instructions.

Quick Start

Prerequisites

• Mendix Studio Pro 11.5+
• .NET 8.0 SDK
• --enable-extension-development flag on Studio Pro

Build & Deploy

dotnet build MCPExtension.csproj

Post-build automatically copies to {YourProject}/extensions/MCP/.

Launch Studio Pro

All flags are required:

studiopro.exe "YourProject.mpr" \
  --enable-extension-development \
  --enable-universal-maia \
  --enable-microflow-generation \
  --enable-workflow-generation \
  --enable-maia-session-story-attachment

Start the MCP Server

Open the MCP dockable pane in Studio Pro (the server starts when the pane opens).

Connect

Endpoint	URL
SSE	http://localhost:3001/sse
Messages	http://localhost:3001/message
Health	http://localhost:3001/health
MCP Metadata	http://localhost:3001/.well-known/mcp

Port auto-increments from 3001 if occupied.

Architecture

Component	File	Purpose
Entry Point	AIAPIEngine.cs	DockablePaneExtension, starts MCP server on pane open
MCP Server	Mcp/McpServer.cs	HTTP/SSE server, tool descriptions & JSON schemas
Tool Wiring	Mcp/MendixMcpServer.cs	Registers all 83 tools, routes calls to implementations
Domain Tools	Tools/MendixDomainModelTools.cs	Entities, associations, attributes, domain model ops
Additional Tools	Tools/MendixAdditionalTools.cs	Microflows, pages, security, workflows, settings
Utilities	Utils/Utils.cs	Module/entity resolution helpers

Dependency Injection (MEF)

Services injected via [ImportingConstructor]:

• IMicroflowService, IMicroflowExpressionService, IMicroflowActivitiesService
• IPageGenerationService, INavigationManagerService
• INameValidationService, IVersionControlService (optional)
• IUntypedModelAccessService (optional, for metamodel escape-hatch)

Tool Reference (83 Tools)

Domain Model — CRUD (15 tools)

Tool	Description
read_domain_model	Read full domain model: entities, attributes, associations, generalizations, event handlers
create_entity	Create entity with attributes. Supports 9 types: persistent, non-persistent, filedocument, image, audit trail variants
create_association	Create association between entities. Cross-module supported
create_multiple_entities	Bulk entity creation with per-entity module targeting
create_multiple_associations	Bulk association creation with cross-module support
create_domain_model_from_schema	Create complete domain model from JSON schema
delete_model_element	Delete entity, attribute, association, or microflow
add_attribute	Add attribute to existing entity (all types including Binary, HashedString, Long)
set_calculated_attribute	Make attribute calculated via microflow
set_entity_generalization	Set entity inheritance (cross-module)
remove_entity_generalization	Remove entity inheritance
add_event_handler	Add before/after event handler (create/commit/delete/rollback)
configure_system_attributes	Toggle system attrs: HasCreatedDate, HasChangedDate, HasOwner, HasChangedBy
diagnose_associations	Troubleshoot association creation issues
arrange_domain_model	Smart layout of entities on domain model canvas

Domain Model — Modify & Rename (11 tools)

Tool	Description
update_attribute	Change type, length, default value, or enumeration of existing attribute
update_association	Change owner, type, delete behavior of existing association
rename_entity	Rename entity (auto-updates all references)
rename_attribute	Rename attribute (auto-updates all references)
rename_association	Rename association (auto-updates all references)
rename_document	Rename any document (microflow, page, constant, etc.)
rename_module	Rename a module (auto-updates qualified references)
rename_enumeration_value	Rename enumeration value
set_documentation	Set documentation on entity, attribute, association, or domain model
read_attribute_details	Detailed attribute info: type details, validation, access rights
query_associations	Query associations by module, entity pair, or direction

Microflows (14 tools)

Tool	Description
list_microflows	List microflows with metadata
create_microflow	Create microflow with parameters and return type
read_microflow_details	Full microflow inspection: parameters, return type, all activities
create_microflow_activities	Create activity sequences (create_object, change_object, retrieve, commit, delete, show_message, close_page)
update_microflow	Update return type, return variable, URL
modify_microflow_activity	Modify existing activity properties by position
insert_before_activity	Insert activity before a specific position
check_variable_name	Check if variable name is available in a microflow
set_microflow_url	Expose microflow as REST endpoint
list_rules	List validation rules across modules
exclude_document	Mark document as excluded/included
copy_model_element	Deep-copy entity, microflow, constant, or enumeration
list_java_actions	List Java actions with parameters
validate_name	Validate candidate name for model elements

Constants & Enumerations (6 tools)

Tool	Description
create_constant	Create constant (string/integer/boolean/decimal/datetime)
list_constants	List constants across modules
update_constant	Modify constant default value or exposed_to_client flag
configure_constant_values	Set constant value overrides per run configuration
create_enumeration	Create enumeration with values and captions
list_enumerations	List enumerations with all values
update_enumeration	Add/remove enumeration values

Pages (4 tools)

Tool	Description
list_pages	List pages with widget count, layout, parameters, documentation
read_page_details	Full page inspection: widget tree, data sources, parameters, actions
generate_overview_pages	Generate CRUD overview pages for entities
delete_document	Delete page, microflow, or any document from module

Nanoflows (2 tools)

Tool	Description
list_nanoflows	List nanoflows with return type, activity count, parameters
read_nanoflow_details	Full nanoflow inspection: parameters, activities, actions

Workflows (2 tools)

Tool	Description
list_workflows	List workflows with context entity, activity count, documentation
read_workflow_details	Full workflow inspection: activities (UserTasks, Decisions, SystemActivities), flows, security

Security (4 tools)

Tool	Description
read_security_info	Project/module security: user roles, module roles, password policy
read_entity_access_rules	Entity access rules: CRUD permissions, XPath constraints, member rights
read_microflow_security	Microflow execution permissions by role
audit_security	Gap analysis: entities without access rules, overly permissive rules

Project & Settings (7 tools)

Tool	Description
read_project_info	Project overview: all modules with entity/microflow/page counts
read_runtime_settings	Read after-startup, before-shutdown, health-check microflows
set_runtime_settings	Assign/clear runtime hook microflows
read_configurations	List run configurations with settings and constant overrides
set_configuration	Create/update run configuration
read_version_control	Version control status: branch, commit, VC type
manage_navigation	Add pages to responsive web navigation

Module & Folder Management (3 tools)

Tool	Description
create_module	Create new module
manage_folders	Create, list, or move documents between folders
sync_filesystem	Import changes from JavaScript actions, widgets, external files

Data & Diagnostics (8 tools)

Tool	Description
save_data	Generate sample data with entity relationships
generate_sample_data	Auto-generate realistic sample data from domain model schema
read_sample_data	Read previously saved sample data
setup_data_import	Wire up sample data import pipeline with Java action
check_model	Validate model for broken generalizations, missing handlers, etc.
check_project_errors	Run mx.exe consistency check (CE error codes)
get_studio_pro_logs	Read Studio Pro and MCP extension logs
get_last_error	Get last error details with stack trace

Meta & Discovery (4 tools)

Tool	Description
list_available_tools	List all 83 tools with capabilities
debug_info	Comprehensive domain model debug info with usage examples
list_scheduled_events	List scheduled events with interval and status
list_rest_services	List published REST services with paths and authentication
query_model_elements	Generic metamodel escape-hatch: query any type by name

Usage Examples

Create a Domain Model

{
  "name": "tools/call",
  "params": {
    "name": "create_domain_model_from_schema",
    "arguments": {
      "module_name": "CRM",
      "entities": [
        {
          "entity_name": "Customer",
          "attributes": [
            {"name": "firstName", "type": "String"},
            {"name": "lastName", "type": "String"},
            {"name": "email", "type": "String"},
            {"name": "isActive", "type": "Boolean"}
          ]
        },
        {
          "entity_name": "Order",
          "entityType": "storecreateddate",
          "attributes": [
            {"name": "orderNumber", "type": "String"},
            {"name": "totalAmount", "type": "Decimal"}
          ]
        }
      ],
      "associations": [
        {
          "name": "Order_Customer",
          "parent": "Order",
          "child": "Customer",
          "type": "Reference"
        }
      ]
    }
  }
}

Create a Microflow with Activities

{
  "name": "create_microflow",
  "arguments": {
    "module_name": "CRM",
    "microflow_name": "CreateCustomer",
    "parameters": [
      {"name": "Name", "type": "String"},
      {"name": "Email", "type": "String"}
    ],
    "return_type": "Boolean"
  }
}

Inspect a Page

{
  "name": "read_page_details",
  "arguments": {
    "page_name": "Customer_NewEdit",
    "module_name": "CRM"
  }
}

Security Audit

{
  "name": "audit_security",
  "arguments": {}
}

Known Limitations

Write Capabilities

The Extensions API has limited write support for some model element types:

• Pages: Only overview page generation (GenerateOverviewPages). No widget-level creation/editing — use read tools for introspection
• Nanoflows: Read-only introspection via untyped model. No creation API
• Workflows: Read-only introspection via untyped model. No creation/editing API
• Log Message Activity: CreateLogMessageActivity does not exist in the Extensions API
• IDomainModelService: Not injectable via MEF (crashes on load). Use entity.GetAssociations() instead

Microflow Activity Quirks

• retrieve and change_object activity types in create_microflow_activities may create the wrong action type — use modify_microflow_activity to fix after creation
• output_variable parameter is ignored during activity creation — set it via modify_microflow_activity
• return_type on create_microflow may not apply — use update_microflow after creation

Troubleshooting

Issue	Solution
Server won't start	Open the MCP dockable pane in Studio Pro
Extension not loading	Verify all --enable-* flags on Studio Pro launch
Port conflict	Server auto-finds next available port from 3001
Connection refused	Check http://localhost:3001/health and Windows Firewall
Tool errors	Use get_last_error for stack traces, check_project_errors for CE codes
Entity type errors	Ensure AIExtension module has required templates (NPE, FileDocument, Image, etc.)

Logs

• MCP debug log: {MendixProjectPath}/resources/mcp_debug.log
• Studio Pro logs: accessible via get_studio_pro_logs tool

Development

Adding a New Tool

1. Implement in MendixDomainModelTools.cs or MendixAdditionalTools.cs
2. Register in MendixMcpServer.cs via _mcpServer.RegisterTool()
3. Add description in McpServer.GetToolDescription()
4. Add JSON schema in McpServer.GetToolInputSchema()
5. Update ListAvailableTools arrays in both tool classes
6. Update registeredTools count in MendixMcpServer.GetStatusAsync()

Dependencies

• .NET 8.0
• Mendix.StudioPro.ExtensionsAPI (11.5)
• Microsoft.AspNetCore (HTTP/SSE server)
• System.Text.Json

License

Experimental — provided as-is for research and development purposes.