rent_vs_buy

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

Annotations provide readOnlyHint=true, but the description adds valuable behavioral context beyond this: it specifies what financial factors are accounted for (mortgage payments, equity, opportunity cost, rent increases, home appreciation) and describes the return format ('which option is cheaper and by how much'), which isn't covered by annotations alone.

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 in two sentences: the first states the purpose and scope, the second details the analysis factors and return value. Every sentence adds essential information with zero waste.

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, 100% schema coverage, annotations indicating read-only operation, and the presence of an output schema, the description provides complete context: it explains the tool's purpose, factors considered, and return format, making it fully adequate for agent understanding.

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?

With 100% schema description coverage, the input schema already documents all 7 parameters thoroughly. The description adds no additional parameter semantics beyond what's in the schema, so it meets the baseline of 3 without compensating for any gaps.

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 with specific verbs ('compare total cost') and resources ('renting vs buying'), and it distinguishes from siblings by focusing on comprehensive financial comparison rather than simple calculations like mortgage_calculator or compound_interest.

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 usage context ('over a given number of years', 'analysis period') and mentions specific factors considered, but doesn't explicitly state when to use this tool versus alternatives like mortgage_calculator or loan_comparison, nor does it provide exclusion criteria.

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