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

Annotations already indicate readOnly, idempotent, and non-destructive behavior, so the description doesn't need to repeat that. It adds value by noting 'on the current federal rules' (implying calculations may change over time) and clarifying that it does not project forgiveness, which sets expectations about the output's scope beyond the annotations.

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 with no wasted words. The main purpose is front-loaded in the first sentence, and the scope limitation is stated concisely in the second. It avoids redundancy with the schema and annotations.

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 has four parameters, all well-documented in the schema, and no output schema. The description explains the core functionality and its limitations. It does not describe the exact return format, but the schema hints at the response echoing qualifying dependents, and the tool's purpose implies a payment amount. Minor gap but not critical for correct 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?

The schema description coverage is 100%, with each parameter thoroughly documented (e.g., familySize explains the qualifying dependent nuance). The tool description itself adds no parameter-specific information, which is acceptable because the schema carries the full burden. Baseline 3 is appropriate since no additional meaning is needed.

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 a specific verb ('estimate') and resource ('RAP monthly payment'), and explicitly differentiates it from sibling comparison tools by noting it is 'not a comparison and no forgiveness projection.' This makes it unambiguous which tool to select for a single RAP payment estimate.

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 explicitly says 'use the plan comparison tool for that' when comparisons or forgiveness projections are needed, which routes the agent to the appropriate sibling. However, it does not explicitly mention the other sibling (compare_married_filing_jointly_vs_separately_student_loans), though that is also a comparison tool and thus covered by the exclusion. The 'current federal rules' also gives temporal context for when to use it.

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