horizon-shield

Verify Fair Price (Signed Receipt)

verify_fair_price

Read-only

工事の適正価格を、検証可能な形(算出内容のSHA-256ハッシュ付き)で返す。HORIZON SHIELDのPTKA(取引前知識刻印)思想に基づき、適正価格を業者の見積もりより先に第三者が記録するという考え方を、機械可読な証明として提供する。エージェントが価格の真正性を検証したい時に使う。 / Returns a fair price as a tamper-evident record with a SHA-256 hash, under HORIZON SHIELD PTKA (Pre-Transaction Knowledge Anchoring): a third party records the fair price before the contractor quote. Japan price data. Use when an agent needs to verify price authenticity.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`work`	Yes	工事名(例: 外壁塗装 30坪)

Output Schema

TableJSON Schema

Name	Required	Description
`count`	No	How many records matched. 0 means the source was read and nothing matched. It never means the source could not be read, that returns isError: true.
`lookup`	No	ok = the source was read and something matched. absent = the source was read and nothing matched. A source that could NOT be read never appears here: that returns isError: true and makes no claim about what does or does not exist.
`provenance`	No	データ出典・監修・再計算手順
`source_read`	No	true on every successful result. A failed lookup does not return a result at all, so this is never false, it is declared so a consumer can assert on it.
`did_you_mean`	No	Near matches, when an exact match was not found.
`verification`	No	claim_sha256, verify_url, ptka
`fair_price_claim`	No	刻印対象の主張(JSON.stringifyしてSHA-256すると claim_sha256 になる)

Schema Changelog

Changes observed during successful MCP inspections.

First observedSep 16, 2026

TDQS

A4.1/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the readOnlyHint annotation, the description adds that the output is a tamper-evident record with a SHA-256 hash and explains the PTKA concept, providing useful behavioral context about the proof mechanism.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is bilingual and relatively concise, but includes a philosophical explanation that is slightly extraneous. It front-loads the core function and structure is clear.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With an output schema present, annotations covering safety, and a single parameter, the description provides sufficient context about the tool's purpose, usage, and underlying concept. It lacks some details about potential error cases, but these are likely in the output schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The single parameter 'work' is fully described in the schema with an example. The description does not add additional parameter semantics, but the schema coverage is 100%, so the baseline of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool returns a fair price as a tamper-evident record with a SHA-256 hash, and explicitly notes its use for verifying price authenticity. This distinguishes it from siblings like get_price_range or audit_estimate, which have different purposes.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explicitly says 'Use when an agent needs to verify price authenticity,' providing a clear usage context. It does not name specific alternatives, but the context is clear enough from the sibling list.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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