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

Annotations already declare a safe read, but the description adds substantial context beyond them: base-currency conversion at the dateTo rate, negative past-due credit notes meaning a Total can be zero or less, totals collapsing to the overdue Total, and a fallback where an unrecognised layout returns the whole report including Current. It also states the required invoice:read scope, which is auth context an agent needs.

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?

Front-loaded with the core purpose and output shape before caveats, and nearly every sentence carries non-obvious information (currency handling, negative credit notes, unrecognised-layout fallback). It is dense and run-on in places, and the routing sentence could have come earlier, but there is little waste.

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?

There is no output schema, yet the description tells the agent what comes back ('Returns report and exchangeRates') and describes the line/column structure and totals, so return-value burden is fully covered. Combined with the auth scope, exclusion of not-yet-due amounts, and fallback behaviour, nothing an agent needs to call it correctly 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 baseline is 3, and the description goes beyond it by establishing that dateTo is the as-of date and the exchange rate date ('as of dateTo ... at the dateTo rate'). dateFrom is never mentioned in the description, leaving one parameter to the schema alone, which keeps it from a 5.

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 verb and resource (get the overdue portion of a company's aged receivables v2 report as of dateTo) and defines the exact shape returned: one group per customer with past-due lines. It explicitly distinguishes itself from get-aged-receivables-v2 and get-invoice-pending-summary, so an agent can choose without opening schemas.

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?

Names both alternatives and the condition that selects each ('use get-aged-receivables-v2 for the full aging or get-invoice-pending-summary for the overdue total only'). It also tells the agent when NOT to expect useful output ('amounts not yet due are left out, so an empty groups list means nothing is overdue').

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