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

No annotations are provided, so the description must convey behavior. It clearly indicates a read operation ('Returns') and specifies the two outputs, but it does not disclose potential edge cases like missing Zestimate data or errors for invalid zpids.

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, concise sentence that front-loads the key purpose and mentions the input and outputs. No wasted words.

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?

The tool has one parameter and two clear outputs, and the description covers both. As a simple read-only valuation retriever with no output schema, the description adequately covers the essential context.

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 already describes zpid as 'Numeric Zillow property id.' The description only adds 'by zpid' which reinforces the parameter's role but does not add new semantic detail beyond the schema. Baseline 3 applies due to full schema coverage.

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 uses 'Returns Zillow's automated valuation (Zestimate) and rent Zestimate' with a specific verb and resource, making it clear this tool retrieves valuation data by zpid. It distinguishes itself from sibling lookup tools which focus on property information.

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 implies usage when a zpid is known and valuation is needed, but it does not explicitly state when to prefer this over the lookup tools or mention any exclusions. No alternative tools are referenced.

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