Show HN: AI-Powered Documentation Generator for Legacy Codebases

[Jonverrier]

https://github.com/jonverrier/McpDoc

As a former CIO who managed teams working with millions of lines of legacy code (Visual Basic, Sybase, Oracle Forms, and worse), I feel the pain of maintaining and onboarding developers to legacy systems.

Believing that LLM-enabled tools can play a role in solving this, I've built a tool that automatically generates documentation for legacy codebases using the Model Context Protocol (MCP) & Claude Sonnet. At first glance, I think this approach has merit. Some samples are in the README. I welcome your thoughts.

The Problem: - Legacy codebases are notoriously difficult to understand and navigate - Onboarding new developers takes months - Making changes safely requires deep knowledge of the system - Business stakeholders lack visibility into system architecture

The Solution - an MCP-based tool that: - Scans your codebase - Generates README files at each level of the directory structure - Creates C4 architecture diagrams showing system components and relationships - Builds a complete documentation hierarchy from high-level architecture to implementation details

The tool aims to helps teams: - Onboard developers faster with clear system documentation - Make changes confidently with better understanding of components - Communicate system architecture to stakeholders - Maintain living documentation that evolves with the codebase

Have a look / try it out!

GitHub: https://github.com/jonverrier/McpDoc License: MIT

To credit various other similar works: https://news.ycombinator.com/item?id=43154065 ( jtwaleson's post) https://news.ycombinator.com/item?id=42521769 https://news.ycombinator.com/item?id=41393458

[axelr340]

Very nice tool Jon!

Do you know about bela.live? I learned that it also creates C4 diagrams from code using AI.

I'm building a tool to help developers understand legacy code by identifying with AI the features implemented in the code, and then displaying these features on a map along with their hierarchy and traceability to code. It's a visual feature-first approach to document software.

Link: https://product-map.ai/

I would love to hear your thoughts about it!

[Jonverrier → axelr340]

Hi,

I had a look at Bela.live. Thanks for the link, it’s obviously very comprehensive. Philosophically, I don’t think these tools should be storing things in their own database - I think the diagrams / markup should be going back to the repo in a format the LLMs can then use for further context.

Your tool is nice, and there is definitely mileage here. I think though if I am honest, my view is the same as with Bela.live : the features you extract should be able to go back to the repo / made available to the models once the developer / product engineer has validated them.

I think that tools that can’t open up fully to bring the models into the workflow as first class participants will be overtaken by those that do.