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

Annotations already declare readOnly, idempotent, closed-world, non-destructive, so the description correctly spends its words elsewhere: 'Free', 'deterministic (no AI inside)', and 'nothing logged' are genuine behavioral facts not present in structured fields. Listing the response envelope (data_confidence, estimated_items, sources, data_version, warnings) is partly redundant with the existing output schema.

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?

Three short sentences, purpose first, then cost/determinism, then response shape. The explicit enumeration of response fields is the only low-value material, since an output schema already exists and the agent will see those fields at call time.

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?

With no parameters, full annotations, and an output schema, the surface area is small and the description covers the essentials: what data it exposes, that it is free and non-AI, and that nothing is logged. The missing piece is workflow guidance, which is scored separately under usage.

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 tool takes zero parameters, so the baseline is 4 and there is nothing for the description to compensate for. The description does not waste space inventing parameter semantics.

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 names the resource — languages for words, Arabic-grammar currencies, and locale notes — but never uses a verb like 'list' or 'returns', leaving the action implied by the name alone. An agent can infer it is a metadata/enumeration tool, but the phrasing 'Languages available for words, the curated Arabic-grammar currencies' is ambiguous about exactly what is enumerated.

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?

There is no guidance on when to call this versus the conversion siblings (number_to_words, amount_to_words, etc.), nor any suggestion such as checking supported languages before requesting word output. The agent must infer the workflow entirely.

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