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

With no annotations, the description carries the burden of behavioral disclosure. It usefully discloses the $0.05 x402 payment requirement and clarifies that output is interpretive judgment rather than live market data. However, it does not describe auth requirements, failure modes, data freshness, or return format details beyond the high-level output components.

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 a single dense sentence that front-loads the price and core value proposition, then efficiently lists the key outputs and caveat. Every clause adds useful information and there is no padding.

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?

Given there is no output schema and no annotations, the description covers the essential context: cost, what the tool produces, the specific curve metrics included, and the caveat that it is analysis rather than a live rate feed. It does not specify the exact response shape, but for an analysis tool this is a reasonable completeness level.

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 describes lookback but leaves x_payment undocumented. The description adds some meaning by mentioning the $0.05 x402 cost, implying x_payment is the payment mechanism. Still, it does not clarify the exact expected value or format of x_payment, leaving a meaningful gap for one of the two parameters.

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 clearly defines the tool as an economist's interpretive read of the US yield curve, listing the exact outputs: regime classification, curve spreads, term premium, historical level comparison, and cited evidence. It also distinguishes itself from a raw rates feed, which separates it from the sibling us_treasury_rates.

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 states that this is 'Judgment, not a rate feed,' which tells the agent when to prefer this tool over raw market data tools. However, it does not explicitly name the alternative tool or provide an explicit 'use this when...' statement, so some inference is required.

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