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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds the returned field set (customer, number, dates, status, totals), the status vocabulary, and the underlying GET /invoices endpoint, but says nothing about pagination behavior or result volume beyond what the schema covers.

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?

Two compact sentences that lead with what the tool lists before the filter axes and endpoint. No filler, though the field/status enumeration is partially redundant with the structured schema.

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 usefully names the fields returned, and it covers all filter dimensions for a 10-param read-only list tool. The remaining gap is pagination expectation (page/per_page defaults live only in 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 90%, so the schema already documents each filter's semantics, including the useful due_to overlap hint. The description restates the filter axes and the status enum without adding format or syntax detail, so it stays at the baseline.

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 (List) and resource (invoices) and enumerates the returned fields plus filterable dimensions, which distinguishes it from teachworks_get_invoice for a single invoice. It stops short of explicitly naming the sibling alternative, so it is clear but not fully differentiated.

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 usage by listing filter dimensions (customer, status, invoice/due date range), so an agent can infer when to apply it, but there is no explicit when-to-use vs get_invoice guidance and no stated exclusions or prerequisites.

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