Get Zillow price history for a property

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

Annotations already mark the operation as readOnly, openWorld, and idempotent. The description adds substantial behavioral detail beyond that: the dual output arrays (events and events_normalized), the fixed type enum, and the critical edge case where empty events plus a note indicate omitted history rather than a genuine absence. This is exactly the kind of contextual disclosure that helps an agent handle responses correctly.

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 three dense sentences with the core purpose front-loaded, followed by output structure and a caveat. Every sentence earns its place, and there is no filler or repetition of the title/name.

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?

Even without an output schema, the description fully explains the return shape (raw events vs. normalized events with the enum) and the important non-Showcase edge case. Combined with the annotations covering safety, idempotency, and open-world behavior, an agent has everything needed to call and interpret this tool correctly.

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 input schema already documents both url and zpid at 100% coverage, so the baseline is 3. The description adds value by clarifying that the two parameters are alternative lookup keys ("by zpid or homedetails URL"), which is a relationship not explicitly stated in the individual schema descriptions. This modest extra semantics justifies a 4.

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 and resource: "Listing-price events for a property" and states the two input identifiers (zpid or homedetails URL). It clearly differentiates this tool from siblings by focusing on listing-price events and explicitly mentioning the same source page as zillow_get_property, which helps distinguish it from property-details and other history tools.

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 provides clear context: it is for retrieving price history events, and it explains the cross-MCP normalized shape, which is a strong usage signal. It also discloses the non-Showcase caveat where history may be omitted. However, it does not explicitly name alternative tools or give when-not-to-use conditions, stopping short of a full 5.

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