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

Annotations only establish that this is a safe read on a closed set; the description goes well beyond them by disclosing the fail-closed listing rule, the no-referral/no-listing-fee neutrality, that pending stores are returned separately, and that a zero-match result is returned honestly rather than padded. These are exactly the behavioral traits an agent needs and cannot get from the schema.

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?

Front-loaded with purpose, then edge-case behavior, then usage routing and triggers, so the ordering is sound. Length is inflated by full Japanese/English duplication, but that is defensible for a bilingual trigger surface rather than pure redundancy.

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?

An output schema exists so return-value documentation is not required, and the description still covers the notable return behaviors (scores/tiers, separate pending list, honest 0 count). Combined with clear invocation routing and a closed-world small-directory caveat, an agent has everything needed to call it correctly.

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 coverage is 100% and both parameters (area, work) carry their own descriptions with examples, so the description adds no syntax or format detail beyond restating that lookup is by area and work name. Baseline 3 is appropriate when the schema does the heavy lifting.

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?

States a specific verb and resource (find verified contractors on the Yakumo directory) and immediately scopes what makes the directory distinct: listing depends only on passing the KIRA audit, fail-closed, no fees. It also implicitly separates itself from the price-oriented siblings (get_price_range, audit_estimate) by declaring it never returns prices.

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?

Explicitly names the precondition and the alternative path: use it after a price check when the user asks who to hire or which contractor can be trusted, and lists trigger phrases in both Japanese and English. It also states when-not: price lookup belongs to get_price_range / audit_estimate, not this tool.

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