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

Annotations already declare readOnlyHint=true, and the description adds useful context beyond that: it returns a snapshot for all counties, includes named sub-components, and notes the update cadence. It does not fully describe behavior like the days parameter's Gold-tier requirement, but that is covered in the schema, so the description adds enough context without contradicting annotations.

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 a single, information-dense paragraph in three sentences. The first sentence packs the core output and scope, the second gives clear use cases, and the third notes the update cadence. Every sentence earns its place, though the long field enumeration makes it slightly less scannable than a two-sentence version.

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?

Despite having no output schema, the description enumerates the return fields (affordability_score, price_to_income, rent_to_income, national_percentile, county_fips, methodology_version), defines the score range, explains county-level coverage, and lists use cases. Combined with the schema's detailed parameter description, the tool is fully understandable and invokable.

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?

The schema has 100% parameter coverage with a well-described optional `days` parameter, so the baseline is 3. The description does not mention parameters, but it doesn't need to; the schema already explains the behavior and tier restriction. The description adds no extra parameter semantics beyond what the schema 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?

The description opens with a specific verb ('Returns') and precisely names the resource: a 0-100 county-level housing affordability score with sub-components and coverage of all 3,222 US counties. It clearly differentiates this tool from the many sibling adw.* indicators by specifying the housing-cost-burden domain and the exact metrics included.

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 gives explicit, actionable use cases: 'Call when the user asks how affordable housing is in a county or how markets compare on cost burden', plus relocation, site-selection, geographic-pay, and housing-investment decisions. It does not explicitly name alternative tools or when not to use it, but the guidance is clear and sufficient for an indicator-lookup tool.

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