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 explains what the tool computes (draw and repayment payments, payment shock, total interest across phases), which goes beyond a generic 'calculate' statement. However, it does not mention assumptions, edge cases, or the exact output format, which would make it more transparent.

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 two sentences, front-loaded with the tool name and purpose, and contains no wasted words. Every clause adds useful information about the phases and outputs.

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?

The tool is moderately complex (7 required parameters, no output schema). The description gives a clear high-level overview of outputs (payments, payment shock, total interest) but does not address parameter meanings or the structure of the returned result. It is adequate but leaves gaps for a user to fully understand 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?

Schema description coverage is 0%, so the description must compensate by explaining parameter meanings and relationships. It only references 'draw' and 'repayment' payments but does not clarify any of the 7 required input parameters (e.g., cltvPct, drawBalance). Parameter names are self-explanatory but the description adds no semantic value beyond them.

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: 'Calculate your HELOC draw and repayment payments' with a specific verb and resource. It also highlights distinctive outputs ('payment shock when interest-only switches to fully amortized, plus total interest across both phases'), setting it apart from sibling calculators like loan_amortization_calculator.

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 when to use the tool (for HELOC payment calculations) but provides no explicit guidance on when not to use it or which alternatives might be better suited (e.g., a basic loan calculator). The context is clear but lacks exclusion or alternative framing.

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