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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the description's real contribution is the gated two-step behavior: it returns a preview plus a confirmation link and only the merchant on that page can commit. That is genuinely valuable beyond the structured fields. However, the sentence about money being integer minor units is irrelevant to a tool with no monetary parameters and adds no behavioral signal.

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 purpose and the no-op-preview warning are front-loaded, which is good, but the parenthetical about integer minor units is dead weight for a language tool and dilutes the message. Three short sentences where two would carry the same information.

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 output schema, the description correctly tells the agent what comes back (a preview of changes and a confirmation link) and who can act on it. Its residual gap is authorization context for the caller itself (whether a non-merchant call errors or just produces a dead link), which an agent would want to know.

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% and the enum descriptions already spell out the meaning of every action and the pt versus pt-BR distinction in far more detail than the prose. The description adds no parameter meaning at all, so the baseline 3 applies.

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?

"Change the shop's languages" names a specific verb and resource, and the description clarifies that the call actually stages a preview rather than committing. It never names the closest sibling (translations_set), so an agent must infer that translation strings are a different tool from language configuration.

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 preview/confirmation flow implies this is the right entry point for any language change, and the action enum in the schema covers the intent variants. There is no explicit statement of when to use this versus translations_set or settings_identity, which are adjacent siblings an agent could easily confuse with it.

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