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

With no annotations supplied, the description carries the full burden and does disclose genuinely useful behavior: the price (€0.0005 per request), the billing/auth mechanism (API key in Authorization: Bearer), and the 20,000-character input ceiling. It omits error behavior for empty/short text and any rate limits, keeping it below a 5.

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 the result and scope, then cost/auth, then the parameter — every clause earns its place and nothing is padded. The telegraphic 'Parameters — text: text' phrasing is the only slight rough edge.

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?

An output schema exists, so return values need little prose, and the description still flags confidence and top-3 candidates. Cost, auth, and input size are covered; the main gap is the semantics of a single optional, nullable parameter on a tool that is useless without it.

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 0%, so the description must compensate, and it only partially does — 'text: text, up to 20 000 chars' adds the length constraint but is otherwise tautological. It does not explain why the sole parameter is nullable and non-required (default null), which is the most confusing aspect of 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+resource ('ISO-639-1 language of a text') and immediately qualifies the output shape (confidence, top-3 candidates) plus the operating envelope (55 languages, works from a few words). No sibling in the list performs language detection, so the risk of confusion with translate or classify is minimal.

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?

Usage is only implied by the purpose statement — an agent can infer this is the tool to reach for when it needs a language code before translate or ocr. There is no explicit when-to-use/when-not guidance, no mention of an alternative, and no note on what to do for ambiguous or mixed-language input.

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