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

Annotations already cover the read-only, idempotent, non-destructive profile. The description adds useful output and aggregation context but does not disclose caveats such as data vintage/revisions or how ambiguous region names are resolved, which would be more valuable in the absence of an output 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?

A single front-loaded sentence packs in the data source, scope, output fields, and invocation hint with no filler. Every clause earns its place.

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 read-only tool with rich annotations, the description covers what will be returned and what input to provide. It could be slightly stronger with an explicit 'not for individual addresses' exclusion or output-shape note, but nothing essential is missing for correct invocation.

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%: the region parameter already carries descriptive examples and the id fallback. The description's 'Pass a region name or id' reinforces but does not add meaning 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 names a specific verb and resource ('Get ... typical home value ... Zillow Home Value Index') plus the exact fields returned (latest, 1-year and 5-year-ago values, percent change). This clearly distinguishes it from sibling real-estate tools like realestate_rents or realestate_trend by data source and aggregation scope.

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?

It clearly establishes the use case: aggregate home values for a metro or state, not property-level or rental data. It tells the caller to pass a region name or id, but does not explicitly name sibling alternatives or state when not to use it.

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