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 but fails completely. 'Get mortgage rates' doesn't reveal whether this is a read-only operation, if it requires authentication, whether it makes external API calls, what format the results come in, if there are rate limits, or any error conditions. For a tool with 8 parameters that presumably queries financial data, this lack of behavioral context is critically inadequate.

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 maximally concise at just three words. While this represents under-specification rather than ideal conciseness, according to the scoring framework, 'Process' received a 2 for being under-specified, but this description is even more minimal. However, given that every word earns its place and there's zero redundancy, it technically meets the criteria for perfect conciseness despite being inadequate in content.

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 (8 parameters, financial data tool), absence of annotations, and no output schema, the description is completely inadequate. It doesn't explain what the tool returns, how results are structured, what authentication might be needed, or any behavioral characteristics. For a mortgage rates tool that likely makes important financial queries, this minimal description fails to provide the necessary context for proper tool usage.

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 schema description coverage is 100%, meaning all parameters are documented in the input schema itself. The description adds no additional parameter information beyond what's already in the schema descriptions. According to the scoring rules, when schema coverage is high (>80%), the baseline is 3 even with no param info in the description, which applies here.

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 'Get mortgage rates' is a tautology that essentially restates the tool name 'mortgagerates_mortgage_rates'. It provides a basic verb ('Get') and resource ('mortgage rates'), but lacks specificity about what kind of mortgage rates (e.g., current market rates, historical rates, personalized quotes) or how they're obtained. Compared to sibling tools like 'market_data_rental_market_trends' or 'zestimate_history_zestimate_history', it doesn't clearly differentiate its scope.

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 absolutely no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites, appropriate contexts, or compare it to any sibling tools (like 'lenderdetails' or 'lendersearch' which might provide related information). There's no indication of when this tool is preferred or what scenarios it's designed for.

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