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

With no annotations, the description carries the full burden and does substantial work: it discloses the three possible return states, the non-obvious meaning of not_registered, and that reads are free and unauthenticated. It does not address failure modes (e.g., neither parameter supplied, unknown domain), keeping it out of the 5 band.

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?

Four tightly packed sentences: purpose first, return values second, the crucial caveat third, and the access model last. Every sentence earns its place and nothing is padding.

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?

No output schema exists, and the description compensates by naming the three return states. The access model is covered. The remaining gap is that zero parameters are marked required, and the description never clarifies whether domain, public_id, or either is needed to resolve a business.

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 of 3 applies. The description adds no format or precedence detail for domain vs public_id (e.g., whether one is preferred or required), so it does not exceed what the schema already provides.

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 (checks whether a business carries Lunara Shield certification) and even enumerates the possible outcomes. It is immediately distinguishable in substance from registry-adjacent siblings, but it never names or contrasts with any of them, so it falls just short of the sibling-aware 5.

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 context is implied rather than stated: the agent learns the lookup is free and unauthenticated, but there is no explicit 'use this when' and no alternatives (applicability, integrity, obligations) are contrasted. The 'do not present as a warning' note is interpretational guidance rather than tool-selection guidance.

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