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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true. The description adds useful context: it covers both accrued interest on public issues and intragovernmental holdings, and it notes the source and that no auth is required. This goes beyond the annotations by clarifying the data scope, which is valuable for an agent deciding whether this tool fits the need.

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 concise (three sentences) and front-loads the essential purpose. It avoids fluff: the first sentence states the core function, the second explains what the data represents, and the third provides source and licensing info. Every sentence adds value, making it highly efficient.

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?

For a low-complexity tool with a single parameter, an output schema, and clear annotations, the description is complete. It explains what data is returned, the breakdown, the source, and the auth requirements. The parameter guidance is sufficient, and the output schema handles return-value specifics, so nothing critical is missing.

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 already documents the limit parameter with a description (schema coverage is 100%), but the tool description adds extra semantic value by providing a concrete example: 'Set limit=50 to get roughly one month of all line items.' This goes beyond the schema's generic description and helps the agent choose an appropriate value, justifying a score above the baseline of 3.

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 exactly what the tool does: retrieves monthly and fiscal-year-to-date US federal interest expense, broken down by security type. It clearly distinguishes it from other treasuryfiscal and treasurydirect tools by specifying the specific data domain (interest expense on debt) and the breakdown dimension.

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 communicates the tool's purpose and the context in which it should be used (when interest expense data is needed), but it does not explicitly mention alternatives or exclusions. However, the clear purpose and the mention of the source (interest_expense) provide enough guidance for an agent to infer 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.