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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: results are returned as one combined table, and currencies are never summed together, which tells the agent to expect per-currency rows rather than a single mixed total.

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 output shape, followed by audience context and the currency caveat. Every sentence carries information, though 'also works with one store' borders on redundant with the schema's 'leave empty if you have only one store.'

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 usefully enumerates the returned columns, which is the key missing piece an agent would otherwise lack. Read-only annotations cover the safety profile, and the currency rule covers the main aggregation pitfall; only limits (e.g., max stores, empty-store behavior) are 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 100%, so all three parameters (store, period, stores) are already documented with enums-like period options and defaults. The description adds only the implicit point that the same period applies to every store; it contributes little parameter-level meaning beyond the schema, so 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?

The description names a concrete output shape (revenue, orders, average order, refunds, top product) scoped to every connected store over one period, which is far more specific than the title alone. It implicitly separates itself from single-store tools by emphasizing 'each connected store,' but it never names a sibling such as compare_periods or get_sales_summary to sharpen the boundary.

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?

'Built for agencies; also works with one store' gives a situational cue for when this tool is appropriate. However, there is no guidance on when to prefer compare_periods or get_sales_summary instead, and no note on whether empty results or unconnected stores are handled silently.

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