list_gb_residential_countries

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

No annotations exist, so the description must carry the full disclosure burden. It states the tool returns 'id + name' and that there is 'No input,' implying a read-only, parameterless operation. However, it does not mention whether results are paginated, sorted, or if authentication is required. The behavioral disclosure is adequate but minimal.

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 description is extremely concise: two sentences with no superfluous words. The first sentence immediately conveys the purpose, and the second adds context. Every sentence earns its place.

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?

Given the tool has no output schema, the description should provide more detail about the return format. It mentions 'id + name' but doesn't specify whether the result is an array of objects, the data types (e.g., string for id), or if there are any restrictions. For a simple list, this is adequate but not fully complete.

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?

The input schema is empty (0 parameters) with 100% schema description coverage. The description confirms 'No input,' which is fully sufficient. Since there are no parameters, the baseline score of 4 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?

The description states 'List the countries (id + name) selectable when creating a GB Residential proxy-request.' It clearly identifies the verb (list), resource (countries), and specific context (GB Residential proxy-request). It also disambiguates from sibling tools by noting 'GB Residential only — ISP fixed-IP plans do not use this.'

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 description explicitly says 'Use to pick a valid country before creating a proxy-request on a GB bucket.' It also clarifies exclusivity: 'GB Residential only — ISP fixed-IP plans do not use this.' This tells the agent when to use and when not to, though it doesn't mention alternative tools for ISP fixed-IP plans.

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