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 returned field set and the backend SOAP call name, but says nothing about auth needs, pagination or volume limits for an invoice with many payments.

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 front-loaded sentence with the resource scope first and the return fields compactly parenthesized; the SOAP method tag is small but useful for debugging. No filler.

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 one-parameter list tool with full schema coverage and complete annotations, this is nearly sufficient: scope and return fields are stated even though no output schema exists. Only the sibling routing and edge-case behavior are absent.

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% for the single invoice_number parameter, so the baseline is a 3. The description confirms the number identifies a sales invoice, reinforcing the schema meaning rather than merely repeating it.

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: payments recorded against one sales invoice, keyed by invoice number, plus the return fields. It implicitly distinguishes itself from kashflow_list_payments_by_date through the per-invoice scope, though it never names that 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?

The usage is implied by 'against one sales invoice... by invoice number', making it clear this is the per-invoice lookup. However, it never states when to use this over kashflow_list_payments_by_date or kashflow_get_invoice, and offers no exclusions or prerequisites.

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