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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, covering the safety profile. The description adds value by specifying return contents: mappings to multiple classification systems and the fields per entry (class ID, name, type, relationship, source). No contradiction with 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?

Three sentences carry purpose, return contents, and use cases without filler. The key scoping ('by its RxCUI') is front-loaded, and the structure is logical. It is dense but not bloated; slightly verbose in enumeration of use cases but appropriate for the tool's complexity.

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 100% schema parameter coverage and a provided output schema, the description is nearly self-sufficient. It explains the multi-system output and typical use cases without needing to restate return types. The omission of class_types like MESH and DISEASE is covered by the schema, so nothing critical 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?

Schema description coverage is 100%, so the schema fully documents all parameters and their options. The description adds some context by expanding classification names, but the schema already includes those expansions (e.g., 'ATC1-4 (WHO Anatomical Therapeutic Chemical)'), so the incremental semantic value beyond the schema is minimal—appropriate for the baseline of 3.

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: 'Retrieve pharmacological and therapeutic classifications for a drug by its RxCUI.' It enumerates the classification systems (ATC, VA, EPC, MOA, PE), which clearly differentiates it from sibling RxNorm tools focused on search, properties, or NDC lookup.

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 provides concrete use cases (therapeutic substitution, formulary management, drug utilization reviews, adverse event analysis), giving an agent clear context for when this tool is relevant. It does not explicitly mention alternatives or exclusions, but the use-case framing is strong enough to guide selection.

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