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
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:
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:
- Real estimate examples are checked against the open construction-cost database (JCCDB) and souba-db to verify fair pricing.
- Overcharge red flags are detected: lump-sum ("一式") line items, inflated overhead, high-pressure same-day closing.
- Each trade gets an integrity score (0-100) and tier (A-F). One overcharged trade lowers the whole result.
- A signed receipt (SHA-256) is attached so anyone can recompute the basis.
- Pricing is monitored after listing; drift alerts the operator.
- 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