ATC Code Details

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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the description doesn't repeat those. It adds value by disclosing the accepted code-length range, level hierarchy, and the endpoint's limitation regarding substance-level codes. It stops short of describing return shape or error handling, but the output schema covers the response.

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 with a leading summary sentence followed by a bullet list of use cases and a final clarification. Every sentence earns its place; no fluff or redundancy. It is appropriately sized for the tool's simplicity.

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 single parameter, the presence of an output schema, and the tool's straightforward nature, the description covers all necessary context: purpose, code-level semantics, exclusions, and a pointer to the alternative tool. No significant gaps remain.

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% and the schema's parameter description already repeats the 1-5 char level constraint and the substance-code exclusion. The description adds semantic enrichment by mapping each code length to its hierarchy level (anatomical, therapeutic, pharmacological, chemical), which aids understanding beyond the regex pattern.

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+resource: 'Look up an ATC code at level 1-4 to get its name and hierarchy level.' It differentiates from sibling tools by explicitly naming atc_classify as the alternative for substance-level codes, making the tool's scope clear.

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 explicit use cases ('Resolve an ATC code', 'Confirm a code exists', 'Identify the level') and an explicit exclusion with a named alternative: 'Substance-level codes (7 chars) are not exposed by this endpoint — use atc_classify'. This is clear when-to-use vs. when-not-to-use guidance.

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