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

The annotations already declare readOnlyHint, openWorldHint, and idempotentHint, so the safety profile is covered. The description adds contextual scope by listing the fact sheet contents and noting current status/price, but it doesn't disclose behaviors like missing fields, freshness, or response size. This is adequate but not rich behavioral disclosure.

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 states the core purpose immediately and then lists concrete examples. Every phrase earns its place; the enumeration is informative without being padded. No redundant restatement of the tool name or title.

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 simple read-only tool with one required parameter and an optional boolean, the description provides enough information for an agent to know what the call returns and what facts to expect. The expand parameter is documented in the schema, and annotations cover idempotence and read-only behavior. It does not describe output structure, but no output schema exists and the listed fields largely cover that.

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 zpid and expand are already well documented. The description adds only general context ('one home') and lists fact types, which maps loosely to the response but not to parameter handling. The baseline of 3 applies because the schema carries the parameter documentation burden.

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 identifies the resource as 'one home' and enumerates the fact categories (beds, baths, living area, etc.), making it clear this is a property-facts lookup. It lacks an explicit verb like 'retrieve' or 'get', but the noun-phrase phrasing still conveys an operation. It differentiates from siblings by emphasizing the full fact sheet for a single home.

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?

No when-to-use or when-not-to-use guidance is provided, and no alternative tools are named. With 18 siblings including zillow_property, zillow_comps, and zillow_nearby_homes, an agent is left to infer which tool to choose. The 'one home' phrasing implies a use case, but the description never explicitly states selection criteria.

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