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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so the safety profile is covered. The description adds useful behavioral detail beyond that: no parameters are required and the result is the set of supported *and enabled* languages, implying the list is dynamic. It does not mention auth requirements, but for a public reference lookup that is minor.

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 well-sectioned, but the markdown scaffolding is heavy for a zero-argument reference lookup, and the idea that language codes feed into hotel search/detail requests is stated twice (Overview and Quick Start). It is readable but not maximally economical.

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 parameterless read-only reference tool with full annotation coverage and no output schema, the description supplies everything needed: what it returns (codes and names), when to use it, and that no input is required. Nothing an agent needs to call it correctly is missing.

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?

There are zero parameters, which sets the baseline at 4. The description confirms 'No parameters required' and the schema is an empty object, so there is no ambiguity to resolve and nothing further the description could add.

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 all supported languages for hotel translations and content localization', and the 'What You Get' section pins down the return content (ISO 639-1 codes, English names). It does not explicitly differentiate itself from the many sibling reference tools like get_data_countries or get_data_currencies, but the resource is unmistakably distinct.

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' block gives four concrete scenarios (language switchers, localization requests, reference validation, displaying options), which is clear context for invocation. It offers no exclusions or alternative-tool routing, so it stops 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.