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

No annotations are provided, so the description carries the full burden. It discloses meaningful side effects (affects profit/ROI app-wide and repricer floors) and the clear-via-zero/empty semantics, which an agent needs to know before mutating. It omits permissions, overwrite behavior, and return shape.

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, then impact, then parameter semantics. Every sentence adds information; no filler.

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 2-required-param mutation with no annotations and no output schema, the description supplies purpose, downstream effects, currency handling, and clearing behavior — enough to call it correctly. Missing auth/permission notes and confirmation of what is returned keep it from being fully complete.

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%, so the description must compensate. It does so well for 'cost' — per-unit price paid, in the user's currency (with a £ example), plus the zero/empty clearing convention. 'sku' is left entirely to the schema, but it is self-evident.

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 (Set) and resource (COG for a SKU) and immediately disambiguates what COG means — 'the per-unit price the user paid'. No sibling tool shares this function, so the agent can route to it confidently.

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?

Explains the downstream context that motivates the call — it 'feeds profit/ROI across the whole app and the repricer's floors' — and explicitly covers the clearing case. It does not name an alternative (e.g. add_purchase) or state when not to use it, so it stops short of full routing guidance.

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