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 states the tool retrieves historical data but doesn't specify whether this is read-only (implied by 'history'), what format the output takes, potential rate limits, authentication needs, or error conditions. 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 a single, efficient sentence that front-loads the core purpose without unnecessary words. It could be slightly improved by adding a brief usage note, but it avoids redundancy and waste, earning a high score for conciseness.

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 moderate complexity (retrieving historical data with two parameters), no annotations, and no output schema, the description is minimally adequate. It states what the tool does but lacks details on output format, error handling, or behavioral traits. With schema coverage at 100%, the description meets a basic threshold but doesn't fully compensate for the missing 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?

Schema description coverage is 100%, with clear documentation for both parameters ('zpid' and 'url'). The description doesn't add meaning beyond the schema, such as explaining the relationship between these parameters (e.g., if one is preferred over the other) or usage examples. Since the schema does the heavy lifting, the baseline score of 3 is appropriate.

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 'Price and Tax history of a property by ZPID'. It specifies the verb ('history'), resource ('property'), and key identifier ('ZPID'). However, it doesn't explicitly differentiate from sibling tools like 'zestimate_history_zestimate_history' or 'propertyv2_property_details_by_zpid', which might offer overlapping or related 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?

No guidance is provided on when to use this tool versus alternatives. The description doesn't mention prerequisites, context, or comparisons to sibling tools (e.g., 'zestimate_history_zestimate_history' for Zestimate trends or 'propertyv2_property_details_by_zpid' for general details), leaving the agent to infer usage based on the name alone.

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