Zillow56 MCP Server

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only states what the tool does ('Zestimate history by zpid') without any information on permissions required, rate limits, data freshness, or what the output looks like (e.g., time series format). For a data retrieval tool with zero annotation coverage, this leaves significant gaps in understanding its behavior.

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 extremely concise at just three words, front-loading the core purpose without any fluff. It efficiently communicates the tool's function, though this brevity contributes to gaps in other dimensions like guidelines and transparency.

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 complexity of retrieving historical property data, no annotations, and no output schema, the description is incomplete. It lacks details on output format, data scope, error handling, and how it differs from sibling tools. The minimal description doesn't provide enough context for an agent to use this tool effectively without additional trial or documentation.

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 description adds no parameter semantics beyond what the input schema provides. Schema description coverage is 100%, with clear documentation for both 'zpid' and 'url' parameters. The description itself doesn't explain parameters, their relationships, or usage examples. Baseline score of 3 is appropriate as the schema adequately covers parameters, but the description doesn't add value in this dimension.

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 the tool's purpose: retrieving Zestimate history for a property using a zpid. It specifies the verb ('Zestimate history') and resource ('by zpid'), making it understandable. However, it doesn't explicitly differentiate from sibling tools like 'price_tax_history_price_and_tax_history' or 'propertyv2_property_details_by_zpid', which might offer overlapping or related property data.

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 no guidance on when to use this tool versus alternatives. It mentions that zpid can be extracted from searching endpoints or property URLs, but this is parameter information, not usage context. There's no mention of when to choose this tool over siblings like 'price_tax_history_price_and_tax_history' or 'rent_estimate_rent_zestimate' for historical property data.

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