wafeq_invoices_line_items_create

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

Goes well beyond the annotations by explicitly warning 'Not idempotent — calling twice creates two records' and explaining the concrete mitigation via idempotency_key with server-side UUID v4 generation. This adds real behavioral context that the idempotentHint=false flag alone does not convey. Consistent with annotations; no contradiction.

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 description is compact, but 'Create invoice line item' and 'Endpoint for creating a new invoice line item' state the same thing redundantly, and the emoji metadata line partially duplicates the title annotation. The important non-idempotency caveat is placed at the end, which is acceptable but not front-loaded.

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?

This is a nested-object create operation with no output schema, yet the description does not mention what the response returns, prerequisites for the parent invoice, or clarify the confusing body parameter description. The strong idempotency guidance partially offsets these omissions, so the tool remains callable, but an agent would be guessing on several key aspects.

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 67%, and the description reinforces the idempotency_key semantics already in the schema. However, invoice_id lacks any schema or description explanation, and the body parameter's schema description is a garbled internal note ('Augment custom_fields in the output with computed CALCULATED field values...') that does not explain what the body should contain. The description does not compensate for these gaps.

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?

The description states a specific verb ('create'), a specific resource ('invoice line item'), and the full endpoint path (POST /invoices/{invoice_id}/line-items/). The invoice-scoped target is unambiguous, distinguishing it from sibling line-item creators on bills, credit notes, quotes, and purchase orders.

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 implies usage ('Endpoint for creating a new invoice line item') but gives no explicit guidance on when to choose this over siblings like wafeq_invoices_line_items_update, wafeq_invoices_line_items_partial_update, or wafeq_invoices_line_items_list. It also omits prerequisites, such as whether the parent invoice must exist or be in a specific state.

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