Zillow56 MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the tool returns data but doesn't mention potential limitations like rate limits, authentication requirements, error handling, or data freshness. For a tool with 10 parameters and no structured safety hints, this leaves significant gaps in understanding its operational 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 functionality. It avoids unnecessary words and directly states the tool's purpose. However, it could be slightly improved by clarifying 'it's' to 'its' for grammatical precision, but this doesn't significantly impact clarity.

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 (10 parameters, no output schema, no annotations), the description is minimally adequate. It explains what the tool returns but lacks details on output format, error conditions, or behavioral traits. The high schema coverage helps, but for a data-fetching tool with many filters, more context on result structure or usage scenarios would enhance completeness.

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%, so the schema fully documents all 10 parameters with examples and enum values. The description adds no parameter-specific information beyond implying that 'address' is used to identify the property and that filters apply to 'comparable properties.' This meets the baseline for high schema coverage but doesn't enhance understanding of parameter roles or interactions.

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: 'Returns a property's rent zestimate and it's comparable properties in the same area.' It specifies the verb ('returns'), resource ('rent zestimate'), and scope ('comparable properties in the same area'), making it easy to understand what the tool does. However, it doesn't explicitly differentiate from sibling tools like 'similar_rent_properties_similar_for_rent_properties' or 'market_data_rental_market_trends', which prevents a perfect score.

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 doesn't mention prerequisites, such as needing a valid address, or compare it to sibling tools like 'similar_rent_properties_similar_for_rent_properties' for similar functionality. Usage is implied by the purpose but lacks explicit context or exclusions.

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