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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety and closed-world behavior are covered, and the description is consistent with them. It adds that the data is 'daily' and 'latest' and that the result carries its own date, which is modest but genuine context. It says nothing about units (percent vs. decimal), update timing, or failure behavior.

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?

Two short sentences, front-loaded with the resource and scope. The second sentence on state tax exemption is tangential to invocation but is short and plausibly relevant context for a rates tool. Nothing is padded or redundant.

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 no parameters and no output schema, the description carries the burden of describing the return value, and it does cover the curve's range and the presence of a date. It omits the output shape (series of maturity/yield pairs?), units, and how often the curve refreshes, which an agent needs to interpret the result. Adequate but with clear gaps.

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 takes zero parameters, so there is no parameter semantics for the description to explain and the baseline of 4 applies. The description correctly implies no filtering options exist by framing the call as always returning the full 1-month-to-10-year curve.

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 names a specific resource and scope: the latest U.S. Treasury daily par yield curve spanning 1 month to 10 years, plus the accompanying date. This is far more than a restatement of the name. It does not, however, distinguish itself from siblings such as get_cash_rates or get_sweep_rate, which also return short-term rate data.

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?

There is no explicit when-to-use guidance, no statement of when to prefer the siblings (compare_after_tax, get_cash_rates, get_sweep_rate), and no prerequisites or exclusions. The only hint is the trailing note about state tax exemption, which gestures toward after-tax comparison without ever naming that alternative or the condition that selects it.

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