Kakao Agentic Player 10 — Jeonse Guardian

Pre-contract checks in a single conversation

For a jeonse lease (Korea’s lump-sum deposit lease, where the tenant pays a large deposit instead of monthly rent), market prices, the property register, special contract terms, and the checks needed at each stage of the contract are all connected, yet each has to be looked up in a different place. Jeonse Guardian (전세지킴이) is an MCP server: enter an address and a deposit, and it calls the tools you need, in sequence, inside the conversation.

It looks up actual transaction prices from the Ministry of Land, Infrastructure and Transport to calculate the jeonse-to-price ratio, and finds risk signals such as mortgages, provisional attachments, and trusts in property register text the user pastes in. From there, I built it out to six tools, covering capacity to recover the deposit, special contract terms suited to the situation, and checklists for before and after signing. The server itself tells the agent, through conversation instructions, which tool to call in what order: confirm the area, diagnose price and risk, check the register, then special terms and checklist.

Responses within 3 seconds

A tool called in the middle of an agent conversation breaks the flow if it is slow. I ran the monthly transaction lookups in parallel, added a cache per area and month, and put a time budget on data collection, so that no path can take more than 3 seconds to respond. Months not fetched within the budget are filled in the background to make the next call faster.

Before deployment, I ran a test script that throws 36 adversarial scenarios, such as typos, unit mix-ups, and malformed input, at every tool, checking crashes, response time, and personal-information exposure in one pass.

Showing the evidence along with the answer

Each result comes back with its data source, lookup period, sample size, and confidence. The register analysis cross-checks keywords in the original text against the parsed result; when they disagree, it lowers the confidence and puts the warning first. The original register text is never stored or logged. Logs keep only the tool name and elapsed time, and personal identification numbers are masked before analysis.

I built and deployed it as an entry to Kakao AGENTIC PLAYER 10; it passed the July preliminary round and is one of 20 finalists, judged by user votes and a jury inside a KakaoTalk tool challenge. It is, however, a tool that provides information for reference and does not replace legal advice. Before signing a real contract, you need the original register and a professional’s review.