HORIZON SHIELD YAKUMO (verified contractor directory)

HORIZON SHIELD YAKUMO

A neutral, verification-gated MCP directory of Japanese renovation and construction contractors.

Yakumo is the contractor-directory layer of HORIZON SHIELD. Only stores that pass an independent fair-price and overcharge audit (KIRA) are listed. Prices are never exposed, only integrity scores and tiers, and unverified stores are never shown to homeowners (fail-closed). Yakumo takes no referral fees from contractors.

• MCP endpoint: https://hearing.horizonshield.dev/mcp (Streamable HTTP, POST JSON-RPC)
• Registry: io.github.ogasurfproject-jpg/hs-hearing
• Operator: The HORIZONs株式会社 / supervised by 大賀俊勝 (Toshikatsu Oga, 30 years in construction, ORCID 0009-0000-9180-903X)
• Backing dataset: JCCDB, an open construction-cost database of 95,403 items (CC BY 4.0)

Tools

Tool	What it does
find_contractor	Free-text discovery orchestrator. Give it a request like "a trustworthy exterior-painting contractor in Aichi" and it infers the area and trade and returns verified stores, or points to fair-price and third-party-check resources if none match.
list_verified_stores	List verified contractors, filterable by area and work. Returns integrity scores and tiers, never prices. Unverified stores are returned separately as pending_stores.
get_contractor_profile	Full verified profile for one store by member_no (e.g. No.001).
mall_overview	The directory at a glance: verified count, work categories, areas, verification method, key links.
how_verification_works	Explains the KIRA audit: fair-price checks, red-flag detection, integrity score and tier, signed receipts, continuous monitoring, fail-closed.

All tool output is JSON. Prices are never returned; trust is expressed as integrity scores (0-100) and tiers (A-F).

Resources

• yakumo://mall: mall overview (JSON)
• yakumo://verification: how verification works (Markdown)
• yakumo://categories: work categories and areas in the directory (JSON)
• yakumo://store/{member_no}: a single store profile (template)

Prompts

• find_a_contractor (area, work): guided flow to discover and vet a verified contractor
• is_this_store_trustworthy (member_no): guided flow to check a store's verification and explain what "verified" guarantees

Argument autocompletion is provided for area and work via completion/complete.

Web widget (WebMCP)

Any site can embed the discovery widget with one line:

<script src="https://hearing.horizonshield.dev/embed.js" async></script>

It renders a Shadow-DOM-isolated panel where a visitor searches verified contractors by area and trade. It stores nothing and shows no prices, only scores and tiers, with links back to the mall and to a free anonymous estimate check.

Discovery and standards

• GET /.well-known/agent-card.json: A2A agent card
• GET /.well-known/security.txt: RFC 9116 contact
• GET /.well-known/glama.json: Glama connector metadata
• Transport compliance: GET/DELETE on /mcp return 405, unsupported MCP-Protocol-Version returns 400, notifications return 202, unknown methods return -32601.

How verification works

Listing is decided only by whether a store passes the independent KIRA audit:

1. Real estimate examples are checked against the open construction-cost database (JCCDB) and souba-db to verify fair pricing.
2. Overcharge red flags are detected: lump-sum ("一式") line items, inflated overhead, high-pressure same-day closing.
3. Each trade gets an integrity score (0-100) and tier (A-F). One overcharged trade lowers the whole result.
4. A signed receipt (SHA-256) is attached so anyone can recompute the basis.
5. Pricing is monitored after listing; drift alerts the operator.
6. Stores that do not pass are never shown to homeowners (fail-closed).

Actual amounts are never published to homeowner-facing pages; they are expressed through scores, tiers, and verification. The final judgment is the homeowner's.

License

Code: see the repository root. Dataset (JCCDB): CC BY 4.0.

Links

• Mall: https://shield.the-horizons-innovation.com/yakumo/
• Join (contractors): https://shield.the-horizons-innovation.com/yakumo/apply/
• Fair-price reference: https://shield.the-horizons-innovation.com/souba/
• Estimate Hacker News (free anonymous check): https://shield.the-horizons-innovation.com/ehn/