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

No annotations exist, so the description carries the full burden and does meaningful work: it bounds the date input (any date since 1990), bounds history (up to 60 days), and discloses that spreads and an inversion flag are computed. It omits error behavior and any rate limits, which keeps it short of a 5.

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 sentences, front-loaded with the resource and coverage, followed by a compact use-case clause. Every phrase (maturity range, unit, date bound, history cap, spreads) carries information an agent needs; nothing is 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?

For a two-parameter read tool with an output schema already documenting return values, the description covers scope, date bounds, history cap, and purpose. The only remaining gaps are minor conventions (exact date string format, observation frequency) that the schema does not supply.

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 0%, so the description must compensate, and it largely does: 'latest day or any date since 1990' scopes the date parameter and 'up to 60 days of history' implies both the purpose and ceiling of the days parameter. It still does not give a date format or say whether days means calendar or business days.

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?

Names the exact resource (US Treasury par yield curve), its maturity span (1 month to 30 years), the unit (percent), and the derived outputs (10y-2y and 10y-3m spreads, inversion flag). An agent can distinguish this from neighbors like fred_series or central_bank_rates without opening the 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?

Explicitly states intended use cases: risk-free rates, discounting, macro analysis, and answering 10-year yield questions. It gives clear positive context but never names a competing sibling (e.g. fred_series) or states when not to use it, so no exclusions are present.

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