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

Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so safety is covered. The description adds genuine non-schema context: no signup/auth required and deterministic output, which tells the agent results are reproducible and credential-free.

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, purpose front-loaded, zero filler. Every clause carries information (what it solves, cost model, operational traits).

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?

No output schema exists, so the description should indicate what comes back (e.g. a single price value) and in what units, but it does not. Combined with 0% schema coverage on four parameters, an agent lacks the detail needed to invoke this confidently.

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% for 4 parameters, so the description carries the full burden. It gestures at the concepts (cost, fees, target margin) but never maps them to parameter names, never says 'cost' is the sole required input, and never states units (fraction vs percent) or defaults for feePct/feeFixed/targetMarginPct.

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: 'Find minimum price for target gross margin after fees', which tells the agent it is a pricing/margin solve rather than a plain margin calculation. It does not explicitly name or contrast with close siblings such as penny_margin or penny_marketplace_profit, so an agent must infer 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?

No when-to-use, when-not-to-use, or alternative routing is given. With siblings like penny_margin and penny_marketplace_profit in the same family, the agent gets no signal about which to pick; usage is only implied by the wording.

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