Create AP2 Fairness Attestation

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

The description discloses key behavioral traits beyond annotations: each call appends one record to the public ledger (making it non-read-only), it does not execute payments, and attestations are independently verifiable via SHA-256, public ledger, and verify_url. This adds meaningful context beyond the readOnlyHint=false annotation, though it does not cover failure modes or authorization requirements.

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

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

The description is comprehensive but redundant due to full bilingual repetition (Japanese and English say the same things). While the content is valuable and front-loaded with safety disclaimers, the parallel duplication makes it longer than necessary, preventing a higher score.

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

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

Given the output schema exists and annotations are present, the description covers all essential context: purpose, side effects (ledger append), scope (Japan construction/renovation, JPY), optional parameter behavior, and verification method. No major gaps remain for an agent to decide when and how to invoke this tool.

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

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

Schema description coverage is 100%, so the baseline is 3. The description adds value by explaining that quoted_price triggers a fair-range verdict (within/above/below) and clarifies that merchant is only reflected in the Cart Mandate example, not used in the judgment. This goes beyond the schema's basic parameter descriptions.

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

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

The description clearly states the tool's core function: it issues a FairPriceAttestation (適正価格の証跡) and explicitly distinguishes it from payment execution by stating it does not initiate, authorize, or move funds. This differentiates it from sibling query/verification tools like get_price_range and verify_fair_price, making the purpose unambiguous.

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

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

The description provides clear usage context: it is a bridge for AP2 agents to attach a price-fairness attestation to a Cart Mandate before asking the user to sign, and passing quoted_price yields a fair-range verdict. However, it does not explicitly mention alternatives or when not to use this tool, so it falls short of a 5.

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