Get Zillow price history for a property

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

The description adds significant behavioral context beyond the annotations: it details the two return arrays (events and events_normalized), explains the normalized type enum, notes the same data source as zillow_get_property, and describes the edge case where history is omitted with a note. Annotations already indicate read-only, open-world, and idempotent, and the description complements them without contradiction.

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 efficiently structured: the first sentence states the purpose, followed by details on output format, normalized shape, data source, and an edge case. Every sentence earns its place with no redundancy.

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?

Given the tool's complexity (two arrays, edge case, no output schema), the description covers the key aspects: what is returned (events and events_normalized), the meaning of the normalized enum, and the note vs empty case. It could be enhanced by explicitly stating that both parameters are optional but at least one should be provided, and by clarifying the raw Zillow shape further if needed.

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%, so the schema already documents both parameters. The description adds value by clarifying that either the zpid or URL can be used and that they refer to a property. This goes beyond the schema's individual descriptions.

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 clearly states it retrieves listing-price events for a property, specifying the types of events and that it works by zpid or homedetails URL. It distinguishes itself from sibling tools like zillow_get_property and zillow_get_zestimate_history by mentioning the same data source and normalized output.

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 when to use the tool (when price history is needed) and provides context on how to use the output (normalized form for merging across MCPs). It also warns about a common edge case (missing history for non-Showcase listings). However, it does not explicitly state when not to use it or name alternatives.

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