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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and openWorld, so the safety profile is covered. The description adds the ISO-2 requirement and that all cities for a country are returned, but says nothing about rate limits, result size, ordering, or error 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?

Front-loaded and skimmable via headers, but the 'What You Get' bullets ('City list', 'City names') are redundant filler for a simple list endpoint, and the use-case bullets overlap heavily. Not wasteful enough to drop below 3, but not tight either.

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-required-parameter read-only list tool with full annotation coverage and no output schema, the description is largely sufficient: it names the input format and the companion endpoint. Missing only minor details like result ordering or volume.

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 both parameters are documented in the schema itself. The description reinforces ISO-2 format with examples ('US', 'GB') and points to the country-code endpoint, which is mildly useful but largely restates the schema.

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 a list of all cities within a specific country.' This clearly distinguishes it from siblings like get_data_countries or get_data_places, which cover different geographic resources.

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?

A dedicated 'When to Use' section gives concrete contexts (dropdowns, location filters, autocomplete) and the Quick Start explicitly routes to the country list endpoint to obtain countryCode. It lacks any 'when not to use' or sibling-alternative guidance, which keeps it from a 5.

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