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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false, and destructiveHint=false, so the safety profile is covered. The description adds only the supported plan names and a minimal return claim (‘Returns: {loan_balance}’), which is largely redundant with the schema and output schema; it does not disclose additional behavior such as calculation basis or output detail.

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 tight sentences and front-loads the core action. The return-value sentence is partly redundant with the output schema, and the list_bundles pointer is peripheral, but overall it is efficient and appropriately sized.

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 a rich input schema, annotations covering safety, and an output schema, the description does enough to identify the tool and its plan scope. The main remaining gap is guidance against the generic or UK student loan siblings, but structurally the necessary information is largely covered by the structured fields.

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 100% and every parameter already has a description, including the enum for plan and the note that annual_income is required for the income_driven plan. The description adds no syntax, format, or dependency detail beyond what the schema already provides, so baseline 3 is appropriate.

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’), resource (‘US student loan repayment’), and supported plan types. The ‘US’ qualifier clearly distinguishes it from calculate_student_loan_repayment and calculate_uk_student_loan, so an agent can identify the right tool without opening siblings.

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 gives no explicit when-to-use or when-not-to-use guidance. The only external pointer is ‘See list_bundles for related finance-us calculators,’ which does not route the agent between the generic student loan tool and this US-specific one.

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