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

Annotations already declare readOnlyHint=true, openWorldHint=true, and idempotentHint=true, covering safety and mutability. The description adds that measure names are resolved for the user and that codes from who_euro_search_measures can be used, which is useful but not extensive. It does not describe potential limitations or data granularity beyond what's stated.

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 and front-loaded, immediately stating what the tool does and what it returns. Every sentence adds value, with no redundant information.

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 tool's moderate complexity and the rich schema (100% coverage), the description is sufficient for an agent to understand the tool's purpose and call it correctly. It doesn't cover all edge cases, but the schema and annotations fill the gaps. Missing details like output format are mitigated by the absence of an output schema.

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 parameters. The description adds that measure names are resolved automatically, which complements but doesn't significantly exceed the schema's parameter descriptions.

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 clearly states the tool fetches time series data for WHO Europe health indicators by country and year, specifying the output includes yearly values, sex breakdown, and units. It distinguishes itself from siblings like who_euro_search_measures and who_euro_countries by focusing on data retrieval, not metadata or country lists.

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 indicates when to use the tool: for European health statistics over time, listing specific domains (mortality, disease incidence, etc.). It does not explicitly mention when not to use it or direct to alternatives, but the context is clear enough given the sibling names.

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