AI Research Assistant for Finding Pokemon Cards on eBay

TL;DR: I wanted to learn how to build AI agent applications, so I made a tool that helps me find and evaluate Pokemon cards on eBay. It searches listings, analyzes photos with AI, and predicts what PSA grade a card might get. Sharing in case it helps others.

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## Why I Built This

Two reasons:

1. I wanted to learn AI agents. Everyone's talking about them, but I learn best by building something real. I needed a project with actual complexity - multiple AI models working together, real-time data, user feedback loops.

2. I needed this for my hobby. I collect Pokemon cards and got tired of the manual research process: searching eBay, opening 50 tabs, squinting at photos trying to spot corner whitening, checking prices across sites. I wanted a research assistant that does the tedious parts.

## What It Does

Mintachu is basically a research assistant for eBay card shopping:

- Search - Find Pokemon card listings on eBay

- Analyze - AI looks at the listing photos and spots condition issues

- Grade - Predicts what PSA grade the card might receive

- Price - Shows market values so you know if it's a good deal

Think of it like having a knowledgeable friend look over your shoulder while you shop.

## The AI Agent Part (What I Learned)

The interesting technical challenge was building a multi-agent system. Instead of one AI doing everything, I have 4 specialized agents:

| Agent | Role |

|-------|------|

| Front Analyzer | Examines the front of the card |

| Back Analyzer | Examines the back of the card |

| Grader | Combines findings into a grade prediction |

| Auditor | Reviews and adjusts the final grade |

Each agent has a specific job and passes its findings to the next one. You can watch them work in real-time - seeing their "thinking" as they analyze the card.

Building this taught me a lot about:

- Prompt engineering for vision models

- Streaming responses to keep the UI responsive

- Coordinating multiple AI calls without timeouts

- Making AI outputs actually useful (not just impressive demos)

## Honest Limitations

- Photo quality from eBay listings varies wildly

- It's a research tool, not a guarantee

- Vintage cards are harder to analyze

- The AI can miss things a human would catch

I use it as a first-pass filter, not a replacement for careful inspection.

## Try It

🔗 [mintachu.com](https://mintachu.com)

Free, no account needed. Would love feedback if you find it useful (or if you don't).

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If you're interested in the technical side - it's Next.js, Gemini Vision API, deployed on Vercel. Happy to chat about the implementation.