List countries

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so the safety profile is covered without the description's help. The description adds that no parameters are required and enumerates the returned fields, but says nothing about caching, rate limits, pagination, or ordering of the list.

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?

A parameter-free reference lookup is expanded into six markdown sections with redundant bullets and marketing filler ('Essential for building country selection interfaces', 'Populate country selection lists'). The 'What You Get' and 'Quick Start' sections largely repeat the Overview.

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 trivial, output-schema-less list endpoint, the description does supply the return content (country names and ISO-2 codes) that an agent would otherwise lack. It is more than sufficient to call the tool correctly, though the return format specifics remain implicit.

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 single 'timeout' parameter is already fully documented by the schema; the description correctly notes 'No parameters required' but adds no information beyond that. Baseline 3 per the rubric.

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 resource ('complete list of all countries') and the payload detail that distinguishes it ('with their ISO-2 country codes'). An agent can tell this apart from get_data_cities, get_data_languages, and get_data_currencies purely from the description.

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 'When to Use' section gives four concrete scenarios (dropdowns, location filters, form inputs, reference data for other endpoints). It gives clear context for calling it but never names an alternative tool or says when NOT to use it, so it falls short of a 5.

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