Add gx mcp server to servers

[davidf9999]

Add gx-mcp-server - Great Expectations MCP Server

Server Details

• Server: gx-mcp-server (new third-party server)
• Changes to: Adding new server entry to README.md third-party servers section

Motivation and Context

Great Expectations is a widely-used open-source Python library for data validation and quality testing. This MCP server
bridges the gap between AI agents and data quality workflows by exposing Great Expectations functionality as MCP
tools. This enables AI agents to:

• Load and validate datasets from various sources (CSV files, URLs, inline data)
• Create data validation suites and expectations programmatically
• Execute data quality checks and retrieve detailed results
• Integrate data validation seamlessly into AI-driven data workflows

How Has This Been Tested?

• ✅ Tested with local MCP clients using HTTP transport
• ✅ All 43 unit tests pass (pytest test suite)
• ✅ Docker smoke tests pass for containerized deployment
• ✅ Validated with Great Expectations v1.5.7+ integration
• ✅ Tested scenarios include: CSV validation, expectation creation, checkpoint execution, result retrieval

Breaking Changes

None - this is a new server addition with no impact on existing functionality.

Types of changes

• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Protocol Documentation
• My changes follows MCP security best practices
• I have updated the server's README accordingly
• I have tested this with an LLM client
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have documented all environment variables and configuration options

Additional context

The server is implemented using FastMCP framework and supports HTTP transport. It's production-ready with comprehensive
error handling, rate limiting, authentication options (Basic Auth, Bearer tokens), and observability features
(OpenTelemetry tracing, Prometheus metrics).

Repository: https://github.com/davidf9999/gx-mcp-server
Version: 2.0.3 (stable release)
Docker: Available at davidf9999/gx-mcp-server:latest

[domdomegg]

Thanks for your contribution! Can you move this to the community servers section?