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

Annotations already cover the safety profile (readOnlyHint=false, destructiveHint=true, idempotentHint=true), so the description's job is to add context, and it does: it discloses real cost ($0.02 per 1,000 original words per target, $0.01 minimum) and that cached reads are free. What it does not explain is why the operation is flagged destructive, e.g. whether it consumes wallet balance irreversibly.

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, front-loaded with the core action before the pricing detail. Nearly every clause earns its place; only the pricing granularity borders on over-precision for a tool-selection description.

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?

Cost and caching behavior are well covered, but with two required parameters at 0% schema coverage and no output schema, the description leaves the accepted target_language format, the meaning of 'eligible', and whether the translation is returned immediately or asynchronously unaddressed.

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% for both parameters. The description says nothing about message_id format or what target_language values are accepted (locale code? language name? one or many?), so the agent must guess the accepted format for the only two inputs.

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: explicitly request paid stored-text translation for an SMS. The word 'request' plus 'stored-text translation' distinguishes it in spirit from the read-only sibling get_message_translations, but the sibling is never named, so the differentiation is left to inference.

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 phrase 'eligible new SMS' and 'cached reads never charge' imply this is for messages not yet translated, but eligibility criteria are never defined and no alternative tool (get_message_translations, request_call_translation) is named as the fallback. Usage is implied rather than stated.

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