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

Annotations already declare readOnlyHint=true and openWorldHint=false, and the description is consistent with a pure, read-only computation. It adds useful output context: the GO/RISKY/NO-GO verdict, the post-VAT/post-fee payout, and the levers (minimum price, max cost, break-even ROAS, max ad cost). It says nothing about how fee/VAT defaults are resolved or how confident the verdict is, which matters because the result depends heavily on those defaults.

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 comes first, then the outputs, then the triggers. The three-sentence structure fits the tool's large input surface. A little redundancy from fixing the brand name and repeating 'margin', but it is still efficient.

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, yet the description spells out the return value well: a verdict tier, the per-sale take-home after VAT, fees, affiliate, payment, returns and social contributions, plus the specific levers and break-even ROAS. For a 21-parameter tool, that level of detail about what comes back is what an agent needs to choose it.

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%, so every parameter — channel, country, ships_from, returns, ad cost — is already documented. The description only echoes the two required inputs ('a selling price and a delivered cost') and does not explain how the 19 optional overrides interact with the country/channel defaults. Baseline 3 is the right call.

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?

Specific verb and resource: takes a price and delivered cost and returns a margin verdict plus breakdown. The stated scope is unmistakable. It never names the compare_channels sibling, so an agent must infer on its own that this tool evaluates one product while the sibling compares several — the only thing keeping it off a 5.

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 final sentence gives concrete triggers: 'if a product is profitable', 'what margin or fees they will have', or 'how to price it'. That covers most realistic intents. It gives no when-not-to-use rule and never points at compare_channels for multi-channel comparisons, so usage is clear but not fully routed.

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