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

With no annotations provided, the description carries the full burden, and it does disclose the main output type: monthly payment plus interest component. However, it omits important behavioral context such as whether the rate is annual or monthly, whether the calculation assumes simple or amortized interest, and what exact output shape is returned.

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 core explanation is short and front-loaded: it states what the tool computes in the first sentence. The second sentence about being a HelpySelf tool is filler that does not help the agent and slightly reduces the signal density.

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?

This is a simple three-parameter calculator, so a short description can be appropriate. However, since there is no output schema, no annotation, and no parameter documentation, the description leaves some conceptual gaps about how the calculation works and what exact result the agent should expect.

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 provides no descriptions for the three required parameters, and the description does not explain units or format for amount, rate, or years. An agent can guess from the tool name that amount is the loan principal, rate is the interest rate, and years is the term, but the description does not definitively guide the agent about how these fields map to the calculation.

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 computes the monthly payment for a loan and the amount of that payment that is interest. This identifies the tool's purpose and distinguishes it from other calculator-like siblings, though it uses the noun 'calculator' rather than an explicit verb like 'calculates.'

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 no guidance about when to use this tool over alternatives. It does not mention when it is appropriate, when it is not, or reference any sibling tools such as compound-interest or salary-calculator tools.

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