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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior. The description adds useful context beyond annotations: it clarifies that language parameter returns official WHO translations only when they exist and that content is never machine-translated. This helps set expectations about localization behavior.

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 concise, front-loaded with the core purpose, and structured with useful bullets that are easy to scan. Every sentence adds value, and there is no redundant restatement of the tool name or generic filler.

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 read-only lookup tool with an output schema and 100% schema coverage, the description is complete. It covers input alternatives, typical use cases, and language behavior. Nothing essential is missing for an agent to select and invoke this tool correctly.

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 all parameter semantics well. The description adds the important relationship that code and URI are alternatives ('Provide either...'), which is not explicit in the schema. However, the language translation nuance is already fully captured in the schema, so the marginal addition is modest.

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?

States a specific verb and resource: 'Get detailed information about a specific ICD-11 entity by code or URI.' This clearly differentiates the tool from siblings like icd11_search (search by text) and icd11_hierarchy (navigation) by emphasizing lookup of a known entity identifier. The bullet list further specifies what kind of information is returned.

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?

Provides explicit use cases: fetching definitions, coding notes, exclusions, official titles, and synonyms. It also gives concrete guidance on inputs ('Provide either an ICD-11 code or a full foundation URI') and language selection. It does not explicitly mention when NOT to use this tool versus alternatives like icd11_search, so it loses a point.

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