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

Annotations only declare readOnlyHint=true, so the description adds real value by disclosing pagination behavior ('Paged: pass next_offset as offset') and the endpoint (GET /invoice). It does not cover auth, rate limits, or result-size implications beyond mentioning fields, so it stops short of 5.

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-loads purpose and returned data before the filter enumeration, paging note, and endpoint. The filter field list is long but necessary because the schema depends on it; a bulleted format would be cleaner but every element earns its place.

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?

No output schema exists, and the description compensates by naming the fields returned (status, totals, credits, payments, balance) and explaining pagination. It omits auth requirements and paging edge cases, but is largely complete for a 5-param list tool.

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, but the description is the sole source of valid filter field names (the schema explicitly defers to 'the list tool's description names the valid ones'). It also clarifies the offset parameter via next_offset, adding meaning 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?

States a specific verb+resource ('List invoices') and enriches it with the returned data shape ('status, totals, credits, payments and balance'). The plural 'List' clearly distinguishes it from the sibling get_invoice without ambiguity.

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?

Implies usage as the invoice listing tool but gives no explicit when-to-use vs get_invoice or other list tools, and no exclusions or prerequisites. The paging note ('pass next_offset as offset') is a helpful operational instruction, but routing guidance is absent.

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