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

Goes well beyond readOnlyHint by explaining that the recorded cost is distrusted and estimated, defining the `state` values (check_cost vs corrected) with the remedy for each, and flagging windowCogs as a period-wide denominator. It also discloses the default 30-day window and the 'never after today' bound.

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?

Purpose is front-loaded and nearly every clause carries information (field meanings, state values, date rule). The field enumeration and em-dash chaining make it a dense single paragraph that is harder to scan than it needs to be.

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, and the description compensates by naming the returned fields and what each means (realisedUnitPrice, recordedUnitCost vs catalogueCost, units, cogs, costedRevenue, windowCogs). Nothing essential for calling or interpreting it is missing.

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 the paired `from`/`to` semantics are already documented; the description adds the operational consequence of omitting them ('reads the last 30 days, which is not that month'), which raises the salience of the constraint. It adds emphasis rather than new syntax, so it stays near 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?

States a precise selection rule: variants sold in the period whose recordedUnitCost is at or above listPriceExVat, plus the exact fields returned. That rule separates it cleanly from siblings like get_margin_trend or get_product_performance, which don't isolate cost-above-price cases.

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?

Gives three concrete trigger questions ('are my costs right', 'why is the margin of product X so low', 'which products sell below cost') and a hard rule that named months/weeks/date pairs MUST be passed. It stops short of naming an alternative sibling for adjacent questions such as overall margin trends.

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