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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety profile is covered. The description adds that results default to the United States profile with the full field set, which is useful context, but says nothing about return shape, ordering, or coverage for sparse country profiles.

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 tight sentences: purpose with examples, usage guidance, then the default behavior. Every sentence carries information and the usage hint is front-loaded after the purpose.

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 one-parameter, no-output-schema discovery tool with full annotation coverage, the description gives enough: what it returns (section and field names), why (to feed factbook_compare), and the default. Only the exact response structure is left implicit, which the examples largely mitigate.

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% and the single parameter's description already states the default of 'United States'. The description's mention of the default and full field set repeats rather than extends schema information, so the baseline 3 applies.

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 ('List') and resource ('sections and field names the CIA World Factbook carries for a country'), with concrete examples like Economy → "Real GDP per capita". It is clearly distinguishable from factbook_compare, which it names.

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 says 'Use before factbook_compare to find the exact field to ask for', giving a clear workflow trigger and naming the alternative. It does not state exclusions or when to skip this step, but the sequencing guidance is concrete.

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