Normalize a country code

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

Beyond the readOnly/idempotent annotations, the description discloses important behavior: matching is case-, accent-, and punctuation-insensitive, and unmatched input yields an error object rather than throwing or guessing. This gives the agent accurate expectations about edge cases.

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 well-structured: a one-sentence definition, accepted inputs, matching behavior, an Args section, and a Returns section. Every sentence earns its place and the most important purpose is front-loaded.

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 lookup tool with annotations and an output schema, the description covers purpose, accepted input variety, normalization rules, and error behavior. Nothing needed for correct invocation is missing.

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 already fully documents the single parameter with examples, so the baseline is 3. The description adds meaning by clarifying normalization behavior and by listing the broader categories of accepted aliases, which helps the agent craft valid inputs.

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 opening sentence uses a specific verb and resource: 'Resolve a country name or code to its ISO 3166-1 alpha-2 code.' It clearly distinguishes itself from the address/message-related sibling tools by domain and by stating its exact transformation.

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 clearly identifies what inputs are accepted (English names, local endonyms, aliases, 2/3-letter codes) and what happens on failure. It does not name an alternative tool or explicitly say 'use this when,' but its acceptance criteria make the intended use unambiguous.

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