listCountries

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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds useful behavioral context beyond annotations: explains pagination, standard filtering, return fields (with active value interpretation), and the URL slug derivation detail. No contradictions.

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 with purpose and usage. Structured with sections for use case, URL slug derivation, pagination/filter, return fields, and system note. Each sentence adds value, though slightly verbose in the filter section.

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 complexity (7 parameters, no output schema but return fields described, rich annotations), the description covers all necessary aspects: purpose, usage, behavior, return values, and system constraints. It is complete for an AI agent to use effectively.

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?

Input schema covers all 7 parameters with descriptions, so baseline is 3. The description adds minimal extra value beyond schema, just noting useful filters like country_code, country_name, active. It does not provide new parameter-level details.

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?

Starts with 'List countries' specifying verb and resource, and adds 'Paginated enumeration of countries in the global reference table. Read-only reference.' This clearly defines the tool's function and distinguishes it from sibling tools like listCities.

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?

Explicitly states when to use: 'Use when: resolving a country name to its 2-letter country_code...or deriving a country URL slug.' It also notes 'System-critical table - create & delete deliberately omitted. Use updateCountry only for corrections.' This provides clear guidance on appropriate contexts and alternatives.

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