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

With no annotations, the description carries the full burden and does disclose important behavioral facts: the holiday scope (national + banking), the DU/(from, to] convention, and a per-call price of $0.005 USDC via x402. It does not cover failure modes or what happens without payment, so it stops short of the top score.

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?

A single dense sentence with the resource, both modes, and the price front-loaded in that order; every clause carries information and nothing is padded.

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 4-parameter, no-annotation, no-output-schema tool it covers the operational essentials (modes, conventions, holiday basis, cost). The one notable omission is the return shape, which no output schema supplies either.

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 baseline is 3; the description goes slightly beyond by grouping parameters into named modes (count uses from/to, add uses date/add), which the flat schema does not label. The DU convention itself is largely repeated from the schema.

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 (Brazilian business-day calculator) and two concrete operations (count between two dates, add N days), plus the holiday basis it uses. An agent can distinguish this immediately from siblings like holidays or bank_lookup.

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 implicitly separates the two modes via their parameter sets, but never states when to reach for this tool versus the sibling holidays or bank_lookup tools, nor any prerequisites. Usage is inferable from the mode descriptions rather than spelled out.

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