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

Annotations already establish read-only, idempotent, open-world behavior, so the bar is lower, and the description still adds real context: it names the upstream data authority and explicitly discloses that principal-person and direct-contact fields are intentionally excluded, which preempts an agent wondering why those fields are absent.

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?

Three tight sentences, front-loaded with purpose, then return contents, then a deliberate exclusion note. Every sentence carries information and there is no 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?

With no output schema, the description helpfully enumerates the return fields (status, expiration, trade, registration type, UBI, locality, freshness source, official link) and flags the intentional field exclusions. It omits match/pagination behavior and any note on source freshness limits, but for a read-only lookup with full annotation coverage it is nearly complete.

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 all three parameters (license_number, business_name, limit) are already documented, including the 'preferred when known' note on license_number. The description restates the exact-vs-partial distinction but adds no format, validation, or behavioral detail beyond the schema, so the baseline 3 applies.

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 gives a specific verb and resource (verify a Washington contractor registration) plus the authoritative source (WA L&I open-data API) and the two lookup keys. It implies a current-state lookup, but it never names its obvious siblings wa_contractor_license_history or wa_contractor_recent_changes, so the agent must infer the routing itself.

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?

Usage is only implied: the agent can tell it's for verification by exact license number or partial business name. There is no explicit when-to-use, when-not-to-use, or alternative named (e.g. history/recent-changes siblings), so the routing guidance rests on inference.

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