previous_business_day

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

Without annotations, the description carries full burden. It clearly states the return value ('first business day strictly before the given date for that country') and notes the effect of extraHolidays. However, it does not disclose any read-only nature or potential rate limits, which is acceptable for a simple lookup.

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 sentences, front-loaded with 'USE THIS', zero waste. Every word is necessary and contributes to understanding.

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 no output schema, the description sufficiently explains what the tool returns. All parameters are described in schema, and the description covers the core behavior. For a simple utility tool, it is 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 baseline is 3. The description adds meaning to 'extraHolidays' by providing an example ('e.g. a company shutdown day'). It does not add much to 'date' or 'country' beyond the schema, but the overall desc adds value.

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?

Description uses a specific verb-resource pair ('find the most recent working day') and distinguishes from siblings like 'next_business_day' by focusing on the 'previous' direction. The phrase 'USE THIS to find... instead of guessing' clarifies its unique role.

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 description implies when to use (before a date/holiday) and provides an alternative ('instead of guessing'), but it does not explicitly exclude other tools like 'next_business_day' or 'is_business_day'. For a straightforward tool, this is adequate but not explicit.

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