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

Adds the single most important behavioral fact that annotations cannot convey: prices are NOT converted, so 1,000 becomes 1,000 in the new currency. It also flags the downstream blast radius (payment gateways and discount codes follow this currency), which meaningfully qualifies the destructiveHint=false annotation by telling the agent the change is value-preserving yet operationally wide-reaching.

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 tight sentences, front-loaded with the core action and immediately followed by the non-obvious gotcha. Every clause carries information: the no-conversion rule, the confirmation requirement, the verification step, and the dependency surface.

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 mutation with no output schema and annotations covering only the safety profile, the description supplies the critical semantics: no conversion, user confirmation, downstream effects, post-check. It does not mention prerequisites (e.g. whether existing orders or configured gateways constrain the change) or what the call returns, leaving a small gap.

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 already documents site_id, the ISO 4217 pattern and examples, and the optional user_goal. The description's restatement of "ISO 4217, e.g. INR" adds no syntax or format detail beyond the schema, so this lands at the baseline.

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 ("Set the currency a store prices, displays and charges in") and immediately binds it to an ISO 4217 code with an example. This is clearly distinguishable from read-only siblings like get_store_settings or adjacent mutations like configure_payments.

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?

Gives explicit when-caution ("confirm with the user when changing an existing store") and a concrete follow-up step ("check prices afterwards"), which is real operational guidance rather than generic boilerplate. It stops short of naming a sibling alternative such as get_store_settings or update_site_settings, so it is not a full 5.

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