atc_lookup

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

Annotations provide readOnlyHint, idempotentHint, etc., describing safety. Description adds that substance-level codes are not exposed, and that output includes name and hierarchy level. Does not contradict annotations.

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?

Description is concise, front-loaded with purpose, uses bullet-like list for usage scenarios. Every sentence adds value without redundancy.

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?

With a simple single-parameter tool and output schema present, description covers all needed context: what returns, level filtering, and exclusion of substance codes.

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% with description. Tool description adds context about acceptable code lengths and levels, plus examples, which enriches meaning beyond the schema.

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 states specific action: 'Look up an ATC code at level 1-4 to get its name and hierarchy level.' Includes examples of inputs and outputs, clearly distinguishes from sibling atc_classify which handles substance-level 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?

Explicitly states when to use: resolve codes, confirm existence, identify level. Tells when not to use: substance-level codes (7 chars) and directs to atc_classify instead.

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