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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is fully covered by structured data. The description adds only that the payload contains a latest typical home value (ZHVI) per matched market; it says nothing about matching behavior, result ordering, or what happens when the query matches nothing. Some added value, but not rich.

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?

Two sentences, zero waste, and the value proposition plus the discovery-before-fetch workflow are front-loaded in that order. Every clause carries information an agent needs.

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 must carry the return-value burden and it does state the key returned metric (latest typical home value) and that region name/id are available for chaining. It is complete enough to call correctly, though it omits anything about the shape of the result set or empty-match behavior.

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 query, type and limit are already documented in the schema, including the enum-like 'metro'/'state' filter and the default-10/max-50 limit. The description only echoes 'by name' and '(metro areas or states)', adding no syntax or format detail beyond the schema; 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?

States a specific verb+resource ('Find real-estate markets (metro areas or states) by name') and explicitly names what is returned ('each one's latest typical home value (Zillow Home Value Index)'). It also names the three sibling tools it is not (realestate_home_values, realestate_rents, realestate_trend), so an agent can separate it from them without opening any schema.

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?

Gives an explicit when-to-use rule: 'Use this to discover the region name/id before calling realestate_home_values, realestate_rents, or realestate_trend.' The alternatives and the condition that selects this tool over them are both stated, leaving nothing to inference.

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