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

Annotations already establish read-only, idempotent, and non-destructive behavior. The description adds useful behavioral context: returned attributes (days late, owed amount, letters sent, next due action) and the ordering by days late descending. It does not mention limit truncation, but that constraint is available in the schema.

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 front-loads the core scope and then enumerates the output fields and ordering. Every clause earns its place, with no filler or redundant restatement of the title.

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 list tool with two optional, well-documented parameters and no output schema, the description sufficiently explains the return content and ordering. The only minor gap is that 'Every' is technically qualified by the `limit` ceiling, but the schema supplies that constraint.

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%, with both `on` and `limit` already documented including format, defaults, and bounds. The description adds no parameter-level meaning beyond what the schema provides, so the baseline of 3 is appropriate.

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 clearly names the resource—unpaid invoices past their due date—and specifies the returned fields plus sort order, so the function is unambiguous. It does not explicitly distinguish itself from sibling tools like aging_summary or chase_today, but the overdue scope and 'worst first' ordering are distinctive.

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 description implies the trigger for use ('unpaid invoice past its due date') and the scope ('Every'), but it gives no explicit when-to-use or when-not-to-use guidance and names no alternatives. The agent must infer how this differs from related invoice tools.

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