business_days_between

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

With no annotations, the description carries the full burden of behavioral disclosure. It clearly states that weekends and US federal holidays are skipped and that dates must be ISO format. However, it does not mention edge cases like whether endpoints are inclusive or what happens when start_date > end_date, leaving some ambiguity.

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 description is two sentences, both of which are informative. The first sentence states the core purpose and behavior, the second provides the necessary date format detail. No wasted words.

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?

Given the tool's simplicity and the presence of an output schema, the description covers the essential aspects: purpose, holiday handling, and date format. The main gap is the lack of specification about endpoint inclusivity or behavior on invalid date ranges, but overall it is reasonably complete for a business-day counter.

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?

The schema coverage is 0%, so the description must compensate. It adds that dates are in ISO format (YYYY-MM-DD), which applies to both parameters, but it does not explain the individual parameter roles beyond their self-explanatory names (start_date, end_date). Since the names are clear and the format note is useful, a score of 3 reflects partial compensation.

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 clearly states the tool counts business days between two dates, with the specific behavior of skipping weekends and US federal holidays. This distinguishes it from siblings like add_business_days (which adds days) and federal_holidays (which lists holidays), making the purpose unambiguous.

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?

The usage is implied: use this tool when you need to count business days between two dates. However, there is no explicit guidance about when not to use it or alternatives (e.g., 'use add_business_days for adding days'). Given the sibling tools, more explicit differentiation would help.

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