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

Annotations already indicate readOnly, idempotent, and non-destructive behavior. The description adds useful behavioral context beyond annotations: daily closes, live versus delayed data based on subscription level, and the free-tier limitation where 'upgrade steps' appear instead of numbers. No contradiction with 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?

A single dense sentence that front-loads the core purpose, then compactly conveys scope (maturity range), frequency (daily closes), and tier-dependent behavior. Every clause provides useful information; no wasted words.

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 zero-parameter tool with no output schema, the description explains what is returned (the whole curve), the covered maturities, and plan-based delivery nuances. It does not describe the exact output shape, but for a simple curve snapshot the missing detail is minor given the clear core purpose.

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 tool has zero parameters and an empty input schema, so the schema fully covers parameter concerns. The description does not need to add parameter semantics, and the no-parameter baseline of 4 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 identifies a specific resource (the entire US Treasury curve, 3M bill to 30Y bond) and implies the action of fetching it in one call. It is clear and distinct from generic curve tools, though it does not explicitly name a sibling to differentiate itself.

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 explains the data freshness tiers (live vs one-hour delayed vs free-tier placeholders) but does not clarify when to choose this tool over siblings like get_curve_history, get_rates_and_curve, or get_yield_closes. No explicit 'when to use' or 'when not to use' guidance is provided.

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