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

The readOnlyHint=true annotation already establishes this is a safe, non-destructive read, so the description only needs to add context beyond that. It does add useful detail — that results include balances and contacts and that the underlying call is GET /api/v1/clients — but says nothing about pagination behavior, result caps, or whether the balance data is computed vs stored.

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 tight sentences with the scope and return contents front-loaded before the endpoint reference. No filler, though the trailing endpoint note is closer to implementation trivia than agent-facing guidance.

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?

There is no output schema, so the description carries some burden of explaining results, and it does mention balances and contacts. However, for a nine-parameter paginated list endpoint it omits pagination semantics and result-shape expectations, leaving the agent to infer how pages interact with per_page and status filters.

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 all nine parameters (including sort syntax, balance operators, and per_page limits) are already documented in the schema. The description restates the name/email/number search axes but adds no syntax or format detail beyond the schema, so the baseline of 3 applies.

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 (clients), and adds scope detail: it returns balances and contacts and supports search by name, email or number. It is distinguishable from invoiceninja_get_client by the plural 'List' framing, but it never explicitly contrasts with that sibling, which keeps it short of a 5.

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: 'List clients' suggests browsing/retrieval, and the search phrase hints at lookup use cases. There is no explicit guidance on when to pick this over invoiceninja_get_client (single client by id) or the other list_* siblings, 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.