MCP Bug Repro Server

Example Use Cases

• 1

  A minimal, reproducible MCP server to test JSON Schema validation behavior (allOf/anyOf) in client apps.

• 2

  Debug or verify Claude Desktop's MCP implementation by running and inspecting concrete tool calls (format_hello, format_goodbye, format_sorry).

• 3

  A simple local test harness to reproduce interoperability bugs and validate fixes before rolling changes into production MCP servers.

Description

This repository implements a small MCP server intended to replicate and demonstrate a bug in how Claude Desktop handles certain JSON Schema constructs (notably allOf/anyOf with objects). It exposes three test tools (format_hello, format_goodbye, format_sorry) that exercise different schema combinations so maintainers can compare which patterns validate correctly. The project is easy to run locally and integrate with Claude Desktop for rapid debugging and validation of fixes. It is useful as a minimal reproducible example for MCP implementers and app developers.