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

Goes well beyond the annotations (which already cover readOnly/idempotent/non-destructive). It discloses that B-READY is a rotating cohort (22 of 41 spine countries in the 2025 edition), that an out-of-cohort country returns the new-company rate alone with a caveat naming the gap, that a country with neither returns NO_DATA, and that every response leads with a not-advice disclaimer. This is exactly the behavioral context an agent cannot infer from structured fields.

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 core purpose is front-loaded and every clause carries real information, but the body is one dense, run-on enumeration that is harder to scan than a broken-out list would be. Appropriate length overall, slightly overwrought in sentence structure.

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 an output schema present, the description needn't explain return values, and it fully covers the tricky cases an agent must anticipate: cohort gaps, the single-rate fallback, NO_DATA, and the mandatory disclaimer. Combined with its parameter routing, an agent has everything needed to call and interpret it 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 coverage is 60%, and the description compensates meaningfully: it defines the country/countries/neither semantics, the default metric (daysDomestic) and the full metric enum, clarifying what each ranking means. It does not explain the `limit` parameter or the sort defaults (those live only in the schema), so it stops short of full coverage.

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+resource: it returns how long and how much it takes to register a limited company, enumerating the exact facts (calendar days, cost, paid-in minimum capital, ownership restrictions, employee quota, online/e-signature status, new-LLC density). The scope is unmistakable and no sibling tool covers company-registration entry, so the agent can pick it without opening the schema.

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?

Gives clear invocation routing: '`country` for one, `countries` to compare, neither ranks by `metric`' with the metric enums listed. However it never states when to prefer this over adjacent siblings like compare_countries or country_dossier, and offers no explicit exclusions — usage is implied rather than guided.

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