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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered elsewhere. The description adds that results carry payment status, total and amount due — useful return context — but says nothing about ordering, pagination behavior, or the fact that searches span number/email/name/phone.

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 compact sentence whose most important information (scope: store vs. customer) is front-loaded, with no filler. It is a fragment rather than a full sentence, but nothing is wasted.

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 7-param tool with no output schema, disclosing the returned fields helps, and defaults/ranges live in the schema. Still missing: result ordering, whether the cursor chain is stable, and any routing to related invoice tools, so an agent could call it correctly but not confidently.

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% with per-parameter descriptions and an enum, so the schema carries parameter meaning. The description only echoes the customer-scope dimension ('of one customer') and the returned fields; it adds no syntax, default, or interaction 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 states the resource (invoices) and its scope: store-wide or for a single customer, plus the fields returned. That distinguishes it from data-focused siblings like list_charges or list_drafts, though it never names an alternative 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?

It implies this is a filtered listing tool but gives no when-to-use guidance or exclusions — nothing about when to reach for list_charges instead, or when resend_invoice is the appropriate follow-up. The agent must infer selection from the tool name alone.

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