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

With no annotations, the description fully bears the burden. It discloses that calculations are deterministic and use dated fee schedules, that results are estimates for eBay and competitors, and that if acquisition_cost is supplied the target is net profit. It also notes per-order fixed fees are applied once, covering important behavioral traits.

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 description is a single paragraph that front-loads the core purpose and then covers usage, exclusions, and caveats. Every sentence adds value, with no redundancy or filler. It is optimally concise for the complexity.

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?

Given 11 parameters and no output schema, the description covers input interpretation, fee methodology, and estimation disclaimers thoroughly. A minor gap is that it doesn't describe the return format (e.g., what values are returned), but the tool is a straightforward computation so this is acceptable.

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 baseline is 3. The description adds meaning beyond the schema, e.g., explaining that quantity affects per-order fixed fees, that shipping_amount affects eBay's fee base, and that acquisition_cost changes the interpretation of target_net. This extra context justifies a score above baseline.

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 specifies a clear verb ('compute the per-item sale price') and resource (trading-card selling methods), and it distinguishes itself from siblings by explicitly saying 'Do NOT use this to look up a card's market value or recent sales', which differentiates it from tools like get_card_price_history.

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 description provides explicit usage scenarios ('when a seller asks what do I need to list this at to walk away with $X') and clear exclusions ('do NOT use it for non-trading-card categories'). It also names an alternative tool indirectly by stating what not to use it for.

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