Check Country Code

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

With no annotations, the description carries the full burden. It clearly states the validation behavior, but does not disclose edge cases such as case sensitivity, whitespace handling, or behavior for non-alpha-2 strings. The output schema may cover return details, but behavioral traits are mostly implied.

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, well-structured sentence that immediately communicates the tool's purpose. There is no wasted wording or redundant 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?

For a simple one-parameter validator, the description is nearly complete: it defines the input standard and purpose. The presence of an output schema reduces the need to describe return values. A note on case sensitivity or non-alpha-2 codes would make it fully complete, but this is a minor gap.

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 only defines code as a string with no description. The tool description fully compensates by explaining that *code* is an ISO 3166-1 alpha-2 country code, giving the parameter complete semantic meaning.

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 states a specific action (check whether) and a well-defined resource (ISO 3166-1 alpha-2 country codes), making it unambiguous. It clearly distinguishes itself from sibling tools like check_currency_code and list_country_codes.

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?

Usage is implied: use this tool to verify if a string is a valid ISO alpha-2 country code. However, it does not explicitly mention alternatives like list_country_codes for enumeration or say when not to use this tool.

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