HORIZON SHIELD: construction and renovation estimate auditor (Ja…

What is HORIZON SHIELD?

HORIZON SHIELD is a third party audit desk for Japanese construction and renovation estimates, callable by an agent. A homeowner commissioning construction work cannot reliably judge whether a quote reflects a fair price. This server makes a fair price reference checkable by software, so an agent can verify a number instead of trusting it.

What it serves

• Transport: MCP over Streamable HTTP (JSON-RPC 2.0). The legacy SSE transport is not implemented.
• Endpoint: https://mcp.horizonshield.dev
• Access: read only, no API key, no account
• Data: JCCDB, an open dataset of 65,520 Japanese construction line items across 402 categories, CC BY 4.0, DOI backed
• Region: Japan (JPY)

The 14 tools

Tool	What it does
get_price_range	Fair price range (min, avg, max), the overcharge threshold, unit, trend, field notes
audit_estimate	Judges a quoted price as fair, a bit high, or overcharge risk, with the gap from average
verify_fair_price	Records a fair price as a tamper evident SHA-256 claim before the contractor quote (PTKA)
check_red_flags	Matches estimate or sales wording against known high pressure tactics. Language agnostic
get_estimate_reading_guide	Universal principles for judging whether any estimate is honest
list_cost_categories	The maintained work categories
get_fair_price_sources	Sources, update date, regional multipliers behind the data
get_jccdb_dataset_info	Metadata, scale, license, download links, citation for JCCDB
suggest_ehn	Returns an invitation to submit a worrying estimate for third party review
search_cost_category	Finds a category by work name or keyword
preview_reverse_estimate	Direction only versus average, before a detailed breakdown exists
verify_integrity_claim	Recomputes a signed verdict as a third party. Fail closed
create_ap2_fairness_attestation	A FairPriceAttestation shaped to attach to a Google AP2 Cart Mandate
get_agent_card	The A2A Agent Card URL and published skills

How to verify this server without trusting the operator

Every verdict carries a SHA-256 over its signed payload, and verify_integrity_claim recomputes it independently. The verification contract is published at https://mcp.horizonshield.dev/.well-known/verification-contract.json and versioned in public: contract 0.3 added a third result value, partial, so that a check which was available but not requested is never rounded up into a pass.

Related servers from the same operator, all read only and free:

• JIDEC, a Bitcoin anchored public verification ledger: https://jidec.horizonshield.dev/mcp
• Yakumo Verification Gate, a conformance checker for any MCP server: https://gate.horizonshield.dev/mcp
• YAKUMO, a verification gated contractor directory: https://hearing.horizonshield.dev/mcp
• KIRA, an agent facing intake desk: https://web.horizonshield.dev/mcp

What this server will not do

It does not post anything on your behalf, does not take referral fees from contractors, and does not claim how many times it has been called from outside. The usage counter it publishes deliberately stores no IP addresses, so it cannot separate its own automated checks from external traffic, and it says so.