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

Annotations already declare the tool read-only, idempotent, and non-destructive, so the description does not need to repeat that. It adds useful behavioral detail by explaining that 'parents' returns ancestors and 'children' returns subcategories, which goes slightly beyond the schema. However, it does not describe output behavior beyond direction semantics, and the output schema covers return structure.

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 compact, front-loaded with the core purpose, and uses a clear bulleted list for use cases. The final sentence adds essential direction clarification 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?

For a simple two-parameter tool with full schema coverage, an output schema, and clear annotations, the description covers everything needed to invoke it correctly. It explains the two directions and the kinds of results to expect, making it complete in context.

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 already documents both parameters well. The description restates the direction semantics already present in the schema but adds no new parameter-level detail or format guidance.

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 uses a specific verb ('Navigate') with a clear resource (ICD-11 hierarchy) and states exactly what it returns: parent and child entities. It distinguishes itself from sibling lookup/search tools by focusing on hierarchical navigation rather than general lookup or search.

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 states when to use the tool: to find broader categories, subtypes, or understand classification structure. It does not explicitly name alternative tools or state when not to use it, but the intended use cases are unambiguous.

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