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 value on top: it explicitly states that no credits are consumed and no data is revealed, and it names the shape of the result (per-action costs for details, ceo, marketing, ecommerce). It does not describe failure behavior for invalid store ids, but that is a minor gap.

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, zero filler, and the most important fact (this is a free preview) is placed immediately after the purpose statement.

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?

There is no output schema, and the description compensates by enumerating the per-action cost keys returned. Combined with a fully documented input schema and safety annotations, an agent has nearly everything needed; only error/edge-case behavior for invalid store ids is 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% and the nested selection object is documented in detail (ids vs tab, filters format, deselected), so the schema carries the semantic load. The description only echoes this with 'for the selected stores' and adds no clarification about which action pricing applies to or how tab selections are priced.

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 opens with a specific verb and resource ('Preview the credit cost of a reveal') and immediately clarifies that it is non-mutating ('Nothing is charged and nothing is revealed'), which implicitly separates it from the sibling revealStores. It stops short of naming revealStores or getRevealStatus explicitly, so the differentiation is inferred 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?

The framing as a 'preview' with nothing charged strongly implies it should be called before the actual reveal, and the returned action breakdown hints at the decision it supports. However, there is no explicit when-to-use statement, no named alternative, and no guidance on what to do with the returned costs.

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