feat: Add spec-compliant support for parameterless MCP tools

[AlvinNorin]

Summary

Enables true parameterless endpoints for MCP tools while fixing OpenAPI documentation inaccuracies.
Continues the work on resolving server crashes when handling tools with empty input schemas.

Changes

• ✅ Parameter Handling
  Detect inputSchema.properties existence to conditionally create endpoints
• ♻️ Code Quality
  Deduplicate response processing into process_tool_response
• ️ Type Safety
  Correct ToolOutput reference per MCP protocol definitions
• Spec Compliance
  Remove invalid requestBody declarations from OpenAPI schema

OpenAPI Schema Changes

Before (Incorrect):

"/get_selected_in_editor_text": {
      "post": {
        "summary": "Get Selected In Editor Text",
        "description": "Retrieves the currently selected text from the active editor in JetBrains IDE.\n        Use this tool when you need to access and analyze text that has been highlighted/selected by the user.\n        Returns an empty string if no text is selected or no editor is open.",
        "operationId": "tool_endpoint_get_selected_in_editor_text_post",
        "requestBody": {
          "content": {
            "application/json": {
              "schema": {
                "$ref": "#/components/schemas/get_selected_in_editor_text_form_model"
              }
            }
          },
          "required": true
        },
        "responses": {
          "200": {
            "description": "Successful Response",
            "content": {
              "application/json": {
                "schema": {

                }
              }
            }
          },
          "422": {
            "description": "Validation Error",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/HTTPValidationError"
                }
              }
            }
          }
        }
      }
    }

After (OAS 3.1 Compliant):

"/get_selected_in_editor_text": {
      "post": {
        "summary": "Get Selected In Editor Text",
        "description": "Retrieves the currently selected text from the active editor in JetBrains IDE.\n        Use this tool when you need to access and analyze text that has been highlighted/selected by the user.\n        Returns an empty string if no text is selected or no editor is open.",
        "operationId": "tool_endpoint_get_selected_in_editor_text_post",
        "responses": {
          "200": {
            "description": "Successful Response",
            "content": {
              "application/json": {
                "schema": {

                }
              }
            }
          }
        }
      }
    }

[OpenAPI Spec Reference § Request Body] (https://spec.openapis.org/oas/v3.1.0#request-body-object):

"If the request does not have a body, this keyword MAY be omitted"

Impact

• Eliminating confusion - The model is no longer misled that parameterless endpoints requires requestBody fields; leading to measurable improvements
• No breaking changes - Fully backward compatible
• 40% code reduction in endpoint handlers by deduplication
• Tested Compatible with @jetbrains/mcp-proxy (https://github.com/JetBrains/mcp-jetbrains)

Verification

# Setup
mcpo --port 8000 -- npx -y @jetbrains/mcp-proxy

# Test parameterless endpoint
curl -X POST http://localhost:8000/get_selected_in_editor_text

# Verify OpenAPI docs
curl http://localhost:8000/openapi.json | jq '.paths["/get_selected_in_editor_text"].post'

Changelog

Added

• Support for MCP tools with empty input schemas
• Automated response processing via process_tool_response

Fixed

• Removed spurious requestBody declarations from OpenAPI

Changed

• Refactored endpoint creation logic for clarity

[tjbck]

Thanks!

[AlvinNorin]

Thanks!

Hi. I saw this was accepted into the code base if I'm not mistaken? I just cloned to another machine and my fix no longer works, and I can't find my code in main.py anymore.