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

With no annotations provided, the description carries the full burden. It honestly discloses the 'today' block, the date_anchor_warning for past dates, and concrete examples of year-mis-resolution flipping the answer (2025-07-20 vs 2026-08-20). This is far beyond a minimal description.

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?

Though a bit long, every sentence adds value: purpose, behavior, warnings, args, examples. It is well-structured, front-loaded with the core function, and the examples are representative. No fluff or redundant phrasing.

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 complexity (relative dates, holiday logic, warnings), the description covers all critical aspects: return content (business day, reason, next business day), the 'today' block, and the date_anchor_warning. An output schema exists, so detailed return field documentation is unnecessary here.

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 description coverage is 0%, so the description must compensate. It does so by defining both parameters: country_code as ISO 3166-1 alpha-2 with examples ('US', 'DE') and check_date as ISO format (YYYY-MM-DD), plus three concrete usage examples that map parameters to real calls.

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 opens with a specific verb and resource: 'Check if a specific date is a business day in a country.' This clearly distinguishes it from siblings like bank_holidays (which likely lists holidays) and value_date (a settlement concept).

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 provides clear context for when to use the tool (any business-day question) and gives important guidance on resolving relative dates against the server's today block. However, it does not explicitly contrast itself with alternative tools, such as saying 'use instead of bank_holidays when you need a yes/no business-day answer.'

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