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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world). The description adds genuinely non-derivable behavior: it discloses that it does not fabricate averages and explicitly reports when no official typical total exists, and that it includes a worked example and payer attribution. Return format/pagination is not described, keeping it at 4 rather than 5.

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 compact sentences with the jurisdiction front-loaded and no filler. The final sentence about not inventing averages earns its place as a trust signal, though the enumeration of covered cost types is somewhat list-heavy.

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?

For a one-parameter, closed-world lookup with no output schema, the description conveys scope, included cost categories, payer attribution, and the handling of missing official data. Only minor gaps remain (e.g., that the response is a fixed statutory dataset rather than a live computation).

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% and the single `state` parameter is fully documented (name or two-letter code) in the schema itself. The description adds no extra constraint or format guidance beyond what the schema already states, 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?

Names a specific resource (US state-mandated closing costs) and enumerates exactly what is covered: transfer and mortgage taxes, recording fees, regulated title premiums, plus who pays each. That scoping implicitly separates it from narrower siblings like transfer_tax_us and title_insurance_us, but no sibling is named explicitly, so it falls short of a 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 is only implied: an agent can infer this applies when a US state's closing costs are needed. There is no statement of when NOT to use it, nor a pointer to the narrower siblings (transfer_tax_us, title_insurance_us, state_overview_us) for single-component questions.

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