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

Annotations already establish read-only, idempotent, non-destructive, closed-world behavior. The description adds meaningful domain behavior: the rate is today's live WSJ Prime plus SBA's capped spread and can be narrowed by loan amount. It does not discuss caching/freshness or output shape, but with annotations present this is solid added context.

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 with the core rate definition front-loaded and the optional parameter second. No redundant or filler wording.

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 simple one-optional-parameter rate lookup with full schema coverage and no output schema, the description supplies the source, scope, and parameter effect. It could be slightly more explicit about the return structure (e.g., rate tiers by loan size), but it is largely complete.

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%, so the parameter's type and 'gross loan amount in dollars' meaning are already documented. The description adds that supplying it returns the cap for that loan, but does not explain tier boundaries or how the cap changes by amount beyond that. Baseline 3 is appropriate.

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—today's maximum variable SBA Express/7(a) rate—and explains it is broken down by loan size and derived from WSJ Prime plus a capped spread. It is distinguishable from estimator/listing siblings, though it does not explicitly name an alternative.

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?

It implies usage for current rate lookup and explains the optional amount, but gives no explicit when-to-use/when-not guidance or point to sibling tools such as get_program_terms or estimate_payment. An agent must infer the selection criteria.

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