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

The formula itself is a strong behavioral disclosure: it tells the agent exactly how the calculation is performed. Combined with the annotations (readOnlyHint=true, idempotentHint=true), this gives a complete safety profile. The only missing piece is edge-case handling (e.g., zero income), but the explicit formula covers the core behavior beyond what annotations provide.

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, succinct line that states the output unit and the formula. No filler words, no redundant content. It is immediately readable and front-loaded with the core concept.

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?

For a simple calculation tool, the description provides the essential purpose, formula, and output unit. The output schema exists, so return values are documented elsewhere. It lacks usage context (covered in dimension 2), but overall it gives enough information for basic selection and invocation.

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 already provides 100% coverage with clear descriptions for monthlyDebt and grossMonthlyIncome. The description adds relational meaning by showing how the parameters interact (numerator and denominator) in the ratio, which goes beyond the individual schema descriptions and clarifies their purpose.

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 explicitly defines the debt-to-income ratio as a percentage with the exact formula (monthly debt / gross monthly income). This is specific, unambiguous, and clearly distinguishes it from sibling financial ratio tools like LTV, DSCR, and cap-rate.

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 usage guidance is provided. The description does not indicate when to use this tool (e.g., loan qualification assessments) or how it compares to alternatives such as mortgage-affordability or debt-payoff. The agent is left without context for selecting it over similar calculators.

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