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

Annotations already declare this a safe read (readOnlyHint=true, destructiveHint=false), so the bar is lower. The description adds genuinely useful context beyond them: page size (up to 100 invoices per page) and an auth requirement (Cotlet API key with access to the Thryv app). It stops short of describing pagination cursor behavior or sort order.

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?

The opening fragment ('Thryv: Invoices from the Sales tab with client, total, balance due and dates') is essentially repeated in the very next sentence, which is pure redundancy. The remaining sentences (unpaid_only, page size, auth) are front-loaded and earn their 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?

For a read-only three-parameter list tool with annotations covering the safety profile and no output schema, the description supplies return fields, filtering, page size and auth needs. Missing only pagination semantics (how to fetch subsequent pages), which an agent will hit given the 100-per-page cap.

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%, so the parameters are already documented. The description's only parameter note ('skip invoices paid in full') merely restates the unpaid_only schema text verbatim, and client_id is not mentioned at all. Baseline 3 applies when the schema does the heavy lifting.

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 (Lists) and resource (invoices from the Sales tab), and enumerates the returned fields (client, total, balance due, dates). It is clearly distinguishable from thryv_create_invoice by verb alone, though it never names a sibling 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?

Usage is implied rather than stated: the tool lists invoices and the description notes unpaid_only filters out fully paid ones. There is no guidance on when to prefer this over other Thryv listing tools (e.g. thryv_list_clients) or any prerequisites/exclusions beyond the API-key note.

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