HORIZON SHIELD - MCP server for construction-estimate integrity (Japan)

An independent, third-party auditor for Japanese construction & renovation estimates. Ask whether a quoted price is fair. It checks the number against a curated fair-price database (souba-db, supervised by Toshikatsu Oga - 30 years in the field), flags known overcharge tactics, and - uniquely - can return a Bitcoin-anchored, independently verifiable signed receipt (PTKA: Pre-Transaction Knowledge Anchoring). The AI doesn't just say "fair" - it hands you cryptographic proof you can verify yourself.

Works with any MCP client: Claude | ChatGPT | Gemini | Perplexity | Cursor | Cline and more.

• Remote endpoint (streamable HTTP): https://hs-mcp.oga-surf-project.workers.dev
• No auth, no install - add the URL as a custom connector.
• Registry name: io.github.ogasurfproject-jpg/horizon-shield
• Operator: The HORIZONs Inc. | https://shield.the-horizons-innovation.com

日本の建設・リフォーム見積もりが適正かを、AIエージェントから「呼べる」中立の第三者監査。相場データ(souba-db／大賀俊勝 実務監修30年)と照合し、過剰請求の赤旗を検知し、Bitcoinに刻印された検証可能な署名レシートまで返す。AIが「適正」と言うだけでなく、誰でも自分で検証できる証拠を出す。

Why it's different

• Verifiable, not just an opinion. Fair prices come with a SHA-256 claim hash and a Bitcoin block anchor (via OpenTimestamps / the JIDEC third-party stamping ledger). Recompute the hash yourself - you don't have to trust the issuer. Conferred verifiability.
• Recorded before the quote (PTKA). A neutral fair price is anchored before the contractor's estimate arrives, so it can't be rewritten to suit the seller.
• Field-supervised data. souba-db is curated from multiple public price sources plus 30 years of on-site experience - not scraped guesses.

Tools (13)

Tool	What it does
get_price_range	Fair price range (min/avg/max), overcharge danger threshold, unit, trend
audit_estimate	Judge a specific quoted amount vs the fair range - verdict, % gap, advice
verify_fair_price	Fair price as a tamper-evident signed receipt (SHA-256 + Bitcoin / PTKA)
red_flag_check	Detect overcharge / high-pressure sales tactics (lump-sum, today-only, etc.)
reverse_estimate_preview	Early-stage preview: which way a rough estimate deviates from average
search_cost_category	Find a construction-cost category by keyword
list_cost_categories	List the curated cost categories
how_to_read_estimate	Universal principles for judging any estimate (overhead ratio, lump-sum, tactics)
fair_price_data_sources	Sources, update date, and regional multipliers behind the data
suggest_ehn	Suggest an EHN (anonymous-estimate) entry
jccdb_dataset_info	JCCDB open dataset (65,520 items, CC BY 4.0) - metadata & citation
verify_integrity_claim	Third-party verification of an issued signed claim (fail-closed)
get_agent_card	A2A (Agent2Agent) agent card for agent interop

Pricing is Japan-specific (JPY). Several tools (red_flag_check, how_to_read_estimate) are language-agnostic and work for estimates anywhere.

Try it

# server info
curl https://hs-mcp.oga-surf-project.workers.dev

# list tools (JSON-RPC 2.0)
curl -X POST https://hs-mcp.oga-surf-project.workers.dev \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

Add it to your AI

• Claude / ChatGPT / Gemini: Settings -> Connectors / Custom apps -> add the remote URL above.
• Programmatic: any MCP client that speaks streamable HTTP JSON-RPC (stateless).

Deploy (maintainer)

The parent folder's wrangler.jsonc points at a different Worker, so cd into this folder first:

cd workers/hs-mcp
npx wrangler deploy   # no bindings, no secrets required

License & data

Tool logic (c) The HORIZONs Inc. Underlying open data: JCCDB (CC BY 4.0). souba-db is a curated reference maintained by HORIZON SHIELD.