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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is known. The description adds value by specifying the computational outputs (balloon balance, total interest) and the relationship between term and amortization, which goes beyond the annotations. It does not contradict the annotations and adds meaningful behavioral context.

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, well-structured sentence that front-loads the core purpose and enumerates the key outputs. It is concise with no filler, effectively conveying all essential information in a compact form.

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?

With no output schema, the description fully explains what the tool returns (monthly and annual debt service, total interest, balloon balance) and gives the typical use case. This is complete for an agent to understand the tool's capabilities and call it correctly, given the read-only annotations.

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 40%, so only the rate parameter has a detailed description (DECIMAL). The tool description explains the concept of term vs. amortization and the balloon balance, which indirectly helps understand termYears and amortizationYears, but it does not explicitly map each parameter to its role. It provides some compensation for the low coverage but not complete guidance.

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 states a specific verb (calculate) and resource (payment math for commercial loans), and explicitly enumerates the outputs (monthly/annual debt service, total interest, balloon balance). It distinguishes itself from siblings like size_loan or calculate_metrics by focusing purely on payment math. The mention of the typical CRE case (10-year term on 30-year schedule) further clarifies 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 clearly indicates this is for loan payment calculations, which is a distinct use case from siblings like stress_test or compare_loan_offers. However, it does not explicitly name alternative tools or state when not to use it, only implying the context through the CRE example. It provides clear context but lacks explicit exclusions.

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