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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds the paging behavior ('paged here') and the underlying SOAP operation name, but says nothing about the shape of returned invoice records or page-size limits (which 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?

One compact sentence with the resource and scoping constraint front-loaded, followed by the implementation note. Slightly telegraphic ('paged here'), but nothing is wasted.

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 a fully documented schema and no output schema, the essentials are present. It is still thin on what the returned invoices contain and how this differs from the general invoice listings, which is the gap an agent would most likely hit.

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 all three parameters already carry their own descriptions including defaults and max values. The description reinforces that customer_id is numeric and that limit/offset produce pages, but adds no syntax or semantics beyond the schema — baseline 3.

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: all sales invoices for one customer, keyed by numeric CustomerID, with paging. It does not explicitly distinguish itself from the siblings kashflow_list_invoices or kashflow_list_unpaid_invoices, so an agent must infer that this is the per-customer scoped variant.

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 usefully routes the agent to kashflow_get_customer for resolving the id, which is real guidance. However, it never says when to prefer this over kashflow_list_invoices, kashflow_list_overdue_invoices, or kashflow_list_unpaid_invoices, so the main sibling choice is left implicit.

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