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

Annotations already cover the safety profile (readOnly, idempotent, closed-world), so the description focuses on value-add: the single rate source, the as-of month stamp, and the current vintage (September 2026). Calling out that these are published ranges rather than deal pricing is genuinely useful disclosure beyond structured fields.

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 tight sentences, front-loaded with what the tool returns and immediately qualified by scope and currency. Every clause earns its place; nothing is repeated from the schema.

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 output schema, the description does the work of sketching the return shape (ranges by program, month-stamped) and the freshness caveat. Only missing element is what happens when 'program' is omitted, which the schema's optionality leaves ambiguous.

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 description coverage is 100% and the 'program' parameter already lists all seven accepted values, so the schema carries the burden. The description only echoes 'by program' without adding format, default-behavior, or multi-value semantics.

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?

States a specific resource (indicative starting rates) and scope (by program, from the site's single rate source). An agent can distinguish it from loan_programs or investor_lenders_aggregate by the 'rates' framing, though no sibling is named explicitly.

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 rather than stated — the reader infers 'call this to see rate ranges.' The 'not pricing on any deal' caveat usefully sets expectations about what the tool is not, but gives no explicit when-to-use or alternative-tool routing.

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