HORIZON SHIELD: construction and renovation estimate auditor (Japan)

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 can return a tamper-evident fair-price receipt: a claim whose SHA-256 anyone can recompute, kept by the issuer at a public URL, under PTKA (Pre-Transaction Knowledge Anchoring). The AI doesn't just say "fair": it hands you a record you can check yourself. What is and is not anchored in Bitcoin is stated below.

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

• Remote endpoint (streamable HTTP): https://mcp.horizonshield.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、誰でも SHA-256 を再計算できる適正価格のレシートまで返す。AIが「適正」と言うだけでなく、誰でも自分で確かめられる記録を出す。Bitcoin に刻印されているのは PTKA の宣言(block 949356)と、データの各版と、2026-10-19 からは毎日のレシートの一覧(前日分を翌日に JIDEC 台帳の 1 entry として刻む)。

Why it's different

• Verifiable, not just an opinion. A fair-price receipt is a claim with its SHA-256 (SHA-256(JSON.stringify(claim))), served by the issuer at https://mcp.horizonshield.dev/ledger/<sha>. Recompute the hash yourself: once you hold it, the claim cannot change without the hash changing. audit_estimate also names the SHA-256 of the souba-db bytes it judged against, and dataset releases are anchored in Bitcoin through the JIDEC ledger (souba-db 2.3.0 = entry 114).
• What is anchored and what is not. The PTKA protocol declaration is anchored in Bitcoin (block 949356, via OpenTimestamps); each receipt carries that block as the protocol it follows. From 2026-10-19 the receipts of each UTC day are listed at https://mcp.horizonshield.dev/ledger/day/<date>, and the next day that list (every receipt that recomputes) becomes one JIDEC ledger entry, stamped to Bitcoin by the ledger's stamping run (.github/workflows/receipt-anchor.yml, copies in ops/receipts/). That bounds a receipt's issue time from above by about a day. Receipts issued before 2026-10-19 were not listed.
• Recorded before the quote (PTKA). A neutral fair price is recorded, with its issue time in the claim, before the contractor's estimate arrives.
• Field-supervised data. souba-db is curated from multiple public price sources plus 30 years of on-site experience - not scraped guesses.

Tools (30)

Fair price, verification and contractors (15)

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 receipt (SHA-256 anyone can recompute, under PTKA)
check_red_flags	Detect overcharge / high-pressure sales tactics (lump-sum, today-only, etc.)
preview_reverse_estimate	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
get_estimate_reading_guide	Universal principles for judging any estimate (overhead ratio, lump-sum, tactics)
get_fair_price_sources	Sources, update date, and regional multipliers behind the data
get_anonymous_estimate_review_link (formerly suggest_ehn, which still answers)	Guide and submission URL for EHN, the free anonymous third-party estimate review board
get_jccdb_dataset_info	JCCDB open dataset (v5.1: 526,128 records = 95,403 items + 430,725 observations, CC BY 4.0) - metadata & citation
verify_integrity_claim	Third-party verification of an issued signed claim (fail-closed)
create_ap2_fairness_attestation	FairPriceAttestation shaped to attach to a Google AP2 Cart Mandate (optional quoted_price adds within/above/below)
get_agent_card	A2A (Agent2Agent) agent card for agent interop
find_verified_contractor	Verification-passed contractors on Yakumo (no referral or listing fee; scores and tiers, never prices)

Fair-price verdicts are Japan-specific (JPY). Several tools (check_red_flags, get_estimate_reading_guide) are language-agnostic and work for estimates anywhere.

Construction cost data: Japan (JCCDB) and both countries (7)

Tool	What it does
search_jccdb_items	Search the JCCDB item catalogue (95,403 line items) by name, with evidence URLs
get_jccdb_observations	Region, date and price status of an item in Japanese and U.S. public documents (licence and source on every row)
get_jccdb_labor_rate	MLIT public-works design labor rates by prefecture and trade
compare_jccdb_regions	Latest value per region for an item and spec (min, median, max)
get_jccdb_work_unit_price	Public-works unit prices for work items with composition ratios
get_jccdb_index_series	Construction cost index series with computed year-over-year change
get_jccdb_coverage	What the observation layers hold, and what is absent

Construction cost data: United States (USCCDB) (8)

USCCDB is the United States Construction Cost Database. The four chain tools (get_us_price_chain, get_us_import_landed_cost, get_us_trade_margins, get_us_contract_discounts) compute on request and are not distributed as files.

Tool	What it does
get_us_construction_prices	U.S. public construction cost data by layer, region, period and item
get_us_prevailing_wage	Davis-Bacon prevailing wages by state, county and trade
get_us_permits	U.S. building permits and declared valuations by region and year
get_us_area_factor	DoD and USACE location cost factors
get_us_price_chain	Estimated U.S. prices from landed import cost to wholesale, retail and contractor (computed on request)
get_us_import_landed_cost	Landed cost of U.S. imports by HS code, duty included
get_us_trade_margins	U.S. wholesale and retail gross margins by NAICS
get_us_contract_discounts	Discount rates off list price in U.S. public contracts

Try it

# server info
curl https://mcp.horizonshield.dev

# list tools (JSON-RPC 2.0)
curl -X POST https://mcp.horizonshield.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).
• stdio clients and registry crawlers: node workers/hs-mcp/stdio.js (from the repository root) relays stdio JSON-RPC to the remote endpoint above. It holds no server code and has no dependencies (Node 18 or later); HS_MCP_URL points it elsewhere. Behind an HTTPS proxy, run it with NODE_USE_ENV_PROXY=1.

Deploy (maintainer)

The server source is not in this repository. The maintainer deploys from a private working tree with this folder's wrangler.jsonc (bindings: RL_KV, HEARING_SVC, JCCDB_SVC); this folder holds the listing metadata and the conformance tests.

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.