HORIZON SHIELD KIRA

Verify Fair Price (Signed Receipt)

verify_fair_price

Returns a SHA-256-hashed fair price for Japanese construction work, creating a tamper-evident record before a contractor quote. Use it to check whether an estimate is overcharged.

Instructions

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.

Changed4 schema fields changedv1.0.11Oct 1, 2026

addedOutput schema / properties / count

Added value: +{
+  "description": "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.",
+  "type": "number"
+}

addedOutput schema / properties / did_you_mean

Added value: +{
+  "description": "Near matches, when an exact match was not found."
+}

addedOutput schema / properties / lookup

Added value: +{
+  "description": "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.",
+  "enum": [
+    "ok",
+    "absent"
+  ],
+  "type": "string"
+}

addedOutput schema / properties / source_read

Added value: +{
+  "description": "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.",
+  "type": "boolean"
+}

Changed1 schema field changedv1.0.1Aug 19, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "additionalProperties": true,
+  "description": "検証可能な適正価格レシート。fair_price_claim(主張)・verification(claim_sha256, verify_url, PTKA)・provenance(出典)。 / Tamper-evident fair-price receipt with hash, verify_url and PTKA anchor.",
+  "properties": {
+    "fair_price_claim": {
+      "description": "刻印対象の主張(JSON.stringifyしてSHA-256すると claim_sha256 になる)"
+    },
+    "provenance": {
+      "description": "データ出典・監修・再計算手順"
+    },
+    "verification": {
+      "description": "claim_sha256, verify_url, ptka"
+    }
+  },
+  "type": "object"
+}

First observedJul 13, 2026

TDQS

A3.6/5.0

Behavior3/5

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

Annotations (readOnlyHint=false, idempotentHint=false) are minimal and don't clarify side effects. The description adds useful context about SHA-256 hashing and the PTKA concept, but it does not explicitly state whether the tool writes a record or is purely read-only, leaving ambiguity about potential side effects—especially since readOnlyHint=false implies it may not be read-only.

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

Conciseness3/5

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

The description is front-loaded with the core action ('Returns a fair price as a tamper-evident record...'), but it includes a lengthy PTKA philosophy explanation that is not strictly necessary for invoking the tool. The bilingual format adds length, making it less concise than optimal while still being structured and informative.

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?

Given that an output schema is present and the tool has only one parameter, the description covers the essential aspects: what it does, the underlying concept, and when to use it. The Japanese price data mention and PTKA context provide useful background without needing to describe return values, which the output schema handles.

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?

Schema description coverage is 100%, and the only parameter ('work') is already described with an example. The tool description does not add any additional meaning or constraints for this parameter, so the baseline score of 3 applies.

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

Purpose4/5

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

The description clearly states the tool's function: returning a fair price as a tamper-evident record with a SHA-256 hash, and explicitly mentions the intended use (verify price authenticity). It does not name a specific sibling alternative like the highest-tier example, but the unique focus on PTKA and hash-based attestation distinguishes it from generic price-lookup tools.

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?

The description provides a clear usage context: "Use when an agent needs to verify price authenticity." This gives a concrete trigger for invoking the tool. However, it does not explicitly exclude cases where other tools (e.g., verify_integrity_claim, get_fair_price_sources) might be more appropriate, nor does it mention alternatives.

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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