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

readOnlyHint=true already tells the agent this is a safe read, so the description is not obligated to restate safety. It adds the REST mapping (GET /api/v1/expenses) and the filterable facets, which is modest added context, but says nothing about pagination defaults or result volume behavior. Adequate but not rich.

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 short sentences, front-loaded with the core action and its filters. The trailing endpoint mapping is marginally redundant, but nothing is padded or buried.

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 an 8-parameter read tool with full schema coverage and no output schema, the description covers the essential purpose and filtering scope. Pagination, sorting, and per-page limits are handled by the schema, so the remaining gap is minor.

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 8 parameters (page, per_page, sort, filter, number, status, client_id, client_status) are already documented in the schema. The description only loosely gestures at client and state filtering without adding syntax or format detail, so the baseline 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 and resource ('List expenses') and names the filtering dimensions, which separates it from sibling list tools like invoiceninja_list_invoices or invoiceninja_list_payments by resource. It does not, however, explicitly differentiate itself from invoiceninja_create_expense or explain why one would choose this list over another expense-related tool.

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 hints at usage via 'filterable by client and invoicing/payment state,' implying you use it when you need expenses narrowed by those facets. There is no explicit when-to-use/when-not guidance and no named alternative, so usage must be inferred.

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