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

With no annotations, the description carries the full burden and does substantial work: it discloses a $0.02 USDC-per-call charge, null-not-interpolated semantics for unpublished tenors, the fixed-snapshot vintage and provenance, and redistribution licensing. It stops short of error behavior for out-of-range dates or the shape of the response, which matters given there is no output schema.

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 price and the core return are front-loaded in the first clause, so an agent learns what it costs and what it gets immediately. The second sentence is a long chain of provenance and licensing detail that is useful but could be tightened.

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 single-parameter data-return tool with no output schema, the description explains what is returned conceptually (14 tenors, nulls preserved) but not the actual response structure or tenor keys. The date-range, vintage, and pricing context is complete, but the return-value contract has a real gap.

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% and the schema already documents the date format, the range, and the default of the latest snapshot date. The description restates the same range and adds only the null/interpolation rule, which is modest value over the schema text.

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 a concrete verb and resource: one paid call returns the full 14-tenor Daily Treasury Par Yield Curve for a single business day. It never names or distinguishes the closely related siblings rates_history, rates_spreads, or rates_schema, so the agent must infer the boundary 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?

Usage is implied through a hard coverage boundary (business days 1990-01-02 through 2026-10-09, nothing after) and the single-business-day scope. There is no explicit statement of when to prefer this over rates_history or rates_spreads, so the agent gets constraints but no routing guidance.

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