List states or cities

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the trailing 'Read-only' restates structured data and earns little. The description does add the useful detail that country accepts a name, ISO code, or id, but it never explains the zero-argument case or whether results are paginated or complete, which matters for a list tool with all-optional params.

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 short sentences, front-loaded with the core capability, then the parameter routing, then the safety note. Nothing is padded and the most decision-relevant information comes first.

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-mode read lookup with a documented schema and no output schema, this covers the essential contract: what it returns (states or cities) and how to select each mode. The unaddressed zero-argument case and the 'name' parameter are the only gaps, and both are minor for a read-only listing tool.

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 67%; 'country' and 'state_id' are documented in the schema and the description mirrors that ('name/code/id'), adding only the name-or-code flexibility which the schema already implies. The third parameter, 'name', is undocumented in both places, and the description gives no indication of what it does, leaving a real gap.

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 plus resource pair — lists states of a country or cities of a state — which is more precise than the generic tool name 'list_regions'. It implicitly separates itself from the sibling list_countries by scoping to sub-country regions, but never names that sibling, so differentiation is left to inference.

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?

'Pass either country (name/code/id) or state_id' gives clear, actionable guidance on which parameter drives which behavior, which is the main usage decision for this tool. What it omits is the failure mode: it does not say what happens if neither is passed (all three params are optional), nor does it point at list_countries as the alternative for country-level results.

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