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

Annotations already flag readOnly=false, destructive=true, idempotent=true and openWorld=true, so the safety profile is covered. The description goes further by disclosing the monetary cost ($0.02 per 1,000 words, $0.01 minimum) and the free cached-read behavior, which is exactly the consequence an agent needs before calling a destructive, billed tool.

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 action and followed by cost and caching facts; each sentence earns its place. Slightly abrupt with no closing note on behavior after invocation.

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 two-parameter, no-output-schema tool with only hint-level annotations, the description covers cost and caching well but leaves 'eligible' undefined, gives no parameter guidance, and does not indicate what the caller receives or what happens on an ineligible/invalid request.

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 required parameters, so the description carries the full burden, yet it says nothing about message_id format or what target_language accepts (locale code? language name?). The only hint is the bare word 'target' in the pricing sentence.

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?

Specific verb (request) plus resource (paid stored-text translation) and scope (an eligible new SMS), which separates it from the read-only get_message_translations sibling. It never names that sibling explicitly, so the differentiation is inferable rather than stated.

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?

'Explicitly request paid ... translation for an eligible new SMS' combined with 'Cached reads never charge' implies the tool is for triggering new translations rather than fetching existing ones, but the when-not condition and the meaning of 'eligible' are never spelled out.

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