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

With no annotations, the description carries the behavioral burden and covers key traits: it discounts weekends and all national/banking holidays, applies the 'start excludes, end includes' convention, and works for any year. It does not describe the exact return shape or behavior when conflicting parameters are provided, but the core behavior is transparent.

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 compact, front-loaded with the core purpose, and every sentence contributes either behavioral detail or parameter routing. No filler or repeated schema content.

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?

All invocation-critical details are present: modes of operation, holiday handling, day-count convention, and parameter requirements. The only gap is that the description does not explicitly state the response format (count vs date), though the tool's name and wording make it strongly inferable.

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 schema already documents each parameter, but the description adds value by marking start_date as mandatory, grouping end_date vs add_days by use case, and instructing the agent to use the exact English parameter names.

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 two precise operations: counting business days between dates and projecting a deadline of N business days. It clearly identifies the domain (weekends plus all national and banking holidays) and distinguishes itself from generic date/calculation siblings.

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 explicitly states which parameters are mandatory or optional and associates end_date with counting and add_days with projecting, so an agent knows how to select the right mode. It does not name alternatives or give exclusion criteria, which prevents a 5.

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