# Fyn — a project by Alejandro Marco

> I built Fyn to explore what property search could become if portals exposed their inventory to AI agents through reliable, structured tools.

- **Type:** Open-source project
- **Role:** Product, design and engineering
- **When:** 2026
- **Human page:** [https://alejandromarco.com/projects/fyn](https://alejandromarco.com/projects/fyn)

## Why I made it

I wanted to test whether an AI could plan a property search while each portal kept control of its data, rules and final experience.

## The project

I’m not trying to replace property portals with Fyn. I’m asking a narrower question: what would become possible if those portals offered official, consent-based interfaces designed for agents?

I made the current product work with public pages and portal-specific behaviour so the interaction is tangible. Its limitations show why stable, authorized agent APIs would be a better destination than teaching models to navigate interfaces built only for humans.

## What I built

### Let the model plan; keep execution deterministic

I let the AI translate a human request into locations, hard constraints and softer preferences. Fyn then validates and executes that plan without running another model in its backend.

### One contract, many imperfect sources

I built a shared connector layer that maps thirteen Spanish property sources into a common listing model while preserving where every result came from.

### Explain the matches—and the failures

I use explicit scoring to explain each match, and expose blocked sources, schema changes, empty results and unavailable coverage instead of hiding them.

### A real MCP surface

I expose the search through a public Streamable HTTP server, so compatible AI clients can call it directly with structured errors, rate limits and an open implementation.

## Scope and limitations

I have no commercial agreements with the portals Fyn explores. I do not present it as a complete property database: it may lose access to a source at any time, and every result must be verified on the original listing. That friction is part of what I wanted the project to reveal.

## Links

- [Try Fyn](https://fynfyn.top)
- [Inspect the source](https://github.com/AlejandroMI/fyn)