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

Annotations already cover the safety profile (readOnlyHint=true, openWorldHint=true, destructiveHint=false), so the bar is lower. The description still adds real context the annotations cannot convey: data is refreshed daily from the Treasury, growth metrics are gated to paid plans, and each call costs 2 credits — all decision-relevant for an agent.

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?

A single dense sentence that front-loads identity, source, and freshness before the returned fields and the cost. Minor waste: the leading 'National Debt: National Debt provides' repeats the title twice before any new information is delivered.

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?

An output schema exists, so return values need not be explained, yet the description still summarizes them usefully. Cost, freshness, and tier gating are all covered; the only gap is the absence of any guidance on historical date usage or rate/failure behavior for a paid, external-source tool.

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 coverage is 100%, so the baseline is 3. The description does explain what the `changes` parameter enables (previous record total plus 1-day/30-day/1-year growth), but that largely restates the schema's own parameter description; the only genuine addition is the paid-plan restriction. The `date` parameter is left entirely to the schema.

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?

States a specific verb+resource — 'provides the US national debt (Debt to the Penny)' — with source ('from the Treasury') and update cadence ('updated daily'). It also enumerates the returned figures, so an agent can distinguish it from neighbors like TreasuryYields, CPIInflation, or GDPData without opening a schema.

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?

Usage is implied rather than stated: you call it to get national debt figures, and the schema note 'omit for current data' hints at historical lookups. There is no explicit when-to-use or when-not-to-use guidance, and no sibling such as TreasuryYields or InflationRate is named as an alternative for related economic queries.

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