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

The description adds real behavioral context beyond the annotations by disclosing the Pro-tier gating and by spelling out the three report sections. It says nothing about permissions, output format, or whether the date range is optional (required parameters is 0), and it sits in mild tension with readOnlyHint=false / idempotentHint=false for what reads as a pure aggregation.

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 that spends every clause on a distinct report section, plus one short tier note. It leads with the date-range scoping rather than the tool's identity, but nothing is wasted or repetitive.

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 carries the full burden of describing return values and does so explicitly across all three sections, including the day-count for late orders. For a two-parameter read-style report this is enough for an agent to call it and interpret the result.

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 both parameters are already documented as YYYY-MM-DD bounds on document date. The phrase 'over a date range' confirms that the range filters document dates rather than, say, delivery dates, but adds no syntax, default, or inclusivity detail beyond the schema.

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 enumerates three concrete outputs — credited-back amounts per currency with invoice counts, still-on-order amounts per currency, and open orders past their delivery date with days late — so the agent knows exactly what the tool produces. It implicitly contrasts with the free list tools (credit_note_list, purchase_order_list) but never names them, so sibling differentiation is present but soft.

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 clause 'Pro; the list tools are free' hints that a free-tier user should route to the list tools instead, which is a partial alternative signal. However, it never states when to prefer this aggregation over those list tools, nor what happens with an omitted or inverted date range.

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