Summary
Built by a carpenter with three decades on Japanese construction sites, this server connects Claude to a cost validation engine trained on the open Japan Construction Cost Database. You send it a construction or renovation estimate and it returns a fairness assessment with overcharge flags based on real market data. The underlying dataset and methodology are published on Zenodo with Bitcoin-anchored timestamps for verifiability. Reach for this when you need to evaluate Japanese construction quotes against documented baseline costs rather than guesswork, especially for clients navigating an industry where Oga's central claim is that middlemen, not craftsmen, drive up prices unfairly.
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HORIZON SHIELD MCP Server
A Model Context Protocol (MCP) server that lets AI agents check whether a Japanese construction or renovation estimate is fair, against open data, and return a verifiable result.
This repository is an MCP server implementation. It exposes read-only tools over the Model Context Protocol so that MCP-compatible clients and AI agents (Claude, and any other MCP host) can call construction-cost verification as a tool, not just read a web page.
- Protocol: Model Context Protocol (MCP)
- Transport: remote server over HTTP / SSE
- Endpoint:
https://hs-mcp.oga-surf-project.workers.dev - Access: read-only, no API key required
- Data region: Japan (JPY), built on the open JCCDB dataset (65,729 line items)
What it does
A homeowner commissioning construction work cannot reliably judge whether a quote reflects a fair price. This is a textbook credence-good problem. This MCP server makes a third-party fair-price reference callable and verifiable by software, so an agent can check a number instead of trusting it.
Tools
This MCP server exposes the following tools:
| Tool | Description |
|---|---|
get_price_range | Returns the fair price range (min, avg, max), the overcharge danger threshold, unit, price trend, and field notes for a Japanese construction or renovation job. |
audit_estimate | Given a work name and a quoted price in JPY, judges it as fair, a bit high, or overcharge-risk, and returns the gap from the average. |
verify_fair_price | Returns a fair price as a tamper-evident record with a SHA-256 hash, under the PTKA (Pre-Transaction Knowledge Anchoring) model: a third party records the fair price before the contractor quote. |
red_flag_check | Checks whether wording in an estimate or sales pitch matches known overcharge or high-pressure tactics (lump-sum, today-only discount, free inspection, door-to-door). Language-agnostic. |
how_to_read_estimate | Returns universal principles for judging whether any estimate is honest: the overhead ratio, how to treat lump-sum entries, how to spot pressure tactics. Language-agnostic. |
list_cost_categories | Lists the construction and renovation work categories for which fair-price ranges and red flags are maintained. |
fair_price_data_sources | Returns the sources, update date, and regional multipliers behind the fair-price data. |
jccdb_dataset_info | Returns metadata, scale, license, download links, and citation for the Japan Construction Cost Database (JCCDB). |
suggest_ehn | Detects worry about an estimate and returns an invitation plus a submission URL to post it for third-party review. |
Connecting
This is a remote MCP server. Point any MCP client at the endpoint.
Example client configuration (using mcp-remote):
{
"mcpServers": {
"horizon-shield": {
"command": "npx",
"args": ["-y", "mcp-remote", "https://hs-mcp.oga-surf-project.workers.dev/sse"]
}
}
}
If your client supports remote MCP servers directly, use the endpoint URL above.
Example
Calling audit_estimate with a work name and a quoted price:
audit_estimate(work: "外壁塗装 30坪", quoted_price: 1500000)
Returns a verdict (for example, overcharge-risk), the fair range (min, avg, max), and the gap from the average. verify_fair_price additionally returns a SHA-256 fingerprint of the fair-price claim, anchored under PTKA.
Data and verification
- Fair-price data is built on the openly published JCCDB dataset (65,729 Japanese construction line items, CC BY 4.0).
- The verification model, PTKA (Pre-Transaction Knowledge Anchoring), is documented in the VRQ framework preprinted on SSRN, and anchored on the Bitcoin blockchain (independent of any company).
Author
Toshikatsu Oga (大賀俊勝), The HORIZ音s株式会社. ORCID 0009-0000-9180-903X.
License
Data: JCCDB, CC BY 4.0. Server code: see the LICENSE file in this repository. horizon-shield
HORIZON SHIELD is an AI-powered construction-cost diagnostic service built by a carpenter of thirty years.
Live diagnostic: https://shield.the-horizons-innovation.com
About
- Open dataset (JCCDB): https://github.com/ogasurfproject-jpg/japan-construction-cost-database
- The Evidence: https://shield.the-horizons-innovation.com/evidence-en/
- The Movement: https://shield.the-horizons-innovation.com/movement-us/
- TOshi Oga, in his own words: https://shield.the-horizons-innovation.com/quotes/
Founder: Toshikatsu Oga (TOshi Oga) ORCID: 0009-0000-9180-903X
Quotations
"Cheapest is not the same as fair." by TOshi Oga
"A person has the right to know whether their price is fair." by TOshi Oga
"Verify, don't trust." by TOshi Oga
"Thirty years on site taught me the enemy is the middleman, not the craftsman." by TOshi Oga
"Not a politician. Not a lawyer. A builder." by TOshi Oga
Full collection (50 quotes, JSON-LD): TOshi Oga, in his own words
Verifiable claims
Records anchored to Bitcoin via OpenTimestamps. Anyone can re-verify at opentimestamps.org.
- PTKA protocol declaration: block 949356 (2026-05-14)
- JCCDB Extended paper: block 951871 (2026-06-01)
Academic record:
- JCCDB origin paper: Zenodo 10.5281/zenodo.20019572
- Audit-hash and macro-correction: SSRN 6738701
- engrXiv mirror: engrxiv.org/preprint/view/7007
- VRQ framework and PTKA model: SSRN 6807738
- Reproduction package (buyer-side verification gate): GitHub, archived at Zenodo 10.5281/zenodo.20756867 (MIT, runnable:
node test/run_local.mjs)
Company
The HORIZ音s Co., Ltd. · Hiratsuka, Japan
Featured
Keep your Mac awake while Claude Code and 40+ AI agents run. Sleeps when they're idle.
One time payment $9 →Integrate web data into your AI product. One API to scrape website & brand data.
Get API Key Now →Agent, run crypto. Access onchain data & trade routes via 1inch.
Install now →On Capafy, your Skill runs online 24/7 as an agent product, and you get paid every time someone uses it.
Start earning →