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

Annotations already establish readOnly/idempotent/non-destructive, and the description adds meaningful behavioral context: the 6K character limit, pricing tiers, the 402 quote behavior, no API key required, optional x-credit-token header, and free daily call. No contradiction with annotations.

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 dense but somewhat redundant: 'up to 6K' appears twice, pricing is stated twice, and 'No API key or subscription' is echoed by 'No wallet or API key required.' It is front-loaded with the core purpose, but it could be tightened without losing meaning.

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?

The description covers purpose, input limits, output format, pricing, authentication, and use cases. A small gap exists: the schema marks 'to' as optional while the description implies both text and to are sent, without explaining what happens if 'to' is omitted. Overall, it is sufficiently complete for an agent to call it correctly.

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 coverage is 100%, so the baseline is 3. The description adds value by noting text can be up to 6K characters, to accepts 'any language,' and the output is only the translation. This goes beyond the schema's minimal 'Target language' and 'Text to translate' descriptions.

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 opens with a specific verb and resource: 'Translate up to 6K chars to any language.' It clearly identifies the tool as a translation primitive and differentiates it from sibling AI tools like ai_extract and ai_summarize by emphasizing it returns pure translation with 'no notes, no wrapper prose.'

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?

It explicitly states when to use the tool: 'Built for agents localizing content, parsing foreign-language sources, or serving multilingual users.' It does not name alternatives or state when not to use it, but the use-case framing is clear enough to route an agent correctly.

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