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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds real value beyond that: it is a POST despite being read-only, it lists the exact returned fields (useful since there is no output schema), and it documents the filter behaviors.

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-first with the returned fields up front, then filter semantics, then the endpoint. Dense but every sentence carries information; only the raw endpoint path is arguably filler.

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?

For a read-only report with no output schema, the description supplies the column list an agent needs to interpret results, and the schema covers as_of, customer_id, max_results and over_due_days. Nothing critical is missing, though pagination/default behavior is left to the schema.

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 all five parameters. The description largely restates those same constraints (empty string = all customers, overdue threshold) without adding new syntax or format detail, so baseline 3 applies.

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 resource and scope: open customer receivables, and enumerates the per-document fields returned (customer, date, due date, total, paid, unpaid). This clearly distinguishes it from merit_customer_payments_report, though it never names that sibling explicitly.

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?

Filter semantics are explained (customer_name/id selection, over_due_days threshold), which implies when the tool applies, but there is no explicit when-to-use guidance nor any routing against siblings like merit_customer_payments_report or merit_sales_report.

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