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

Annotations already cover read-only, idempotent, non-destructive, closed-world behavior, so the description only needs to add context — and it does: no key is required for baseline output, an authenticated call returns your own rate, and the response covers edge cases (nothing sells, delivery fails). It does not describe output shape or units, but with the safety profile already declared this is solid added value.

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?

A single dense sentence with a parenthetical enumeration, front-loaded with the usage trigger "Before you sell" and followed by the auth caveat. Every clause carries information; the only cost is density — the fee components are packed into one long clause rather than listed.

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?

With no output schema, the description must convey what comes back, and it does: fee breakdown, Stripe fee range, listing fee, and no-sale/failed-delivery outcomes. All three parameters are optional and fully schema-documented, and annotations cover the safety profile. Only the numeric format of the returned figures is unstated.

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%, so the schema already documents currency, price_minor and reseller_share_pct fully. The description hints at the price input ("at a price") and the reseller share ("reseller share") but adds no syntax, defaults, or bounds beyond the schema. Baseline 3 is appropriate when the schema carries the parameter burden.

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 states concretely what the tool returns: the net proceeds of one paid sale at a given price, broken into PazAIr fee, reseller share, Stripe card fee range, plus the listing fee and failure/no-sale behavior. That is a specific computational purpose, not a restatement of the name. It stops short of naming how it differs from adjacent siblings like price_hint or how_to_earn.

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?

"Before you sell" implies the usage moment (pre-listing fee estimation), which is genuine guidance but only implicit. It does not say when to prefer this over price_hint or sales_statement, nor does it name any alternative. The auth note explains a variant of the same call rather than an alternative tool.

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