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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true. The description adds useful behavioral context beyond annotations: the endpoint is GET /line_items, the tool returns specific fields, and it notes that the API reference does not state the unit for amount/quantity—a valuable caveat.

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 a single dense sentence that front-loads the purpose and packs in useful field details plus the endpoint. It is appropriately sized, though the field list is somewhat compressed.

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?

With no output schema, the description helpfully lists the returned fields and notes the unit ambiguity. The input schema fully covers filters and pagination, and annotations cover safety, so the definition is nearly complete; explicit pagination-response behavior is the main minor gap.

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 limit, offset, event_id, booking_id, and invoice_id are already well documented. The description lists booking_id, event_id, and invoice_id as returned fields rather than clarifying their role as filters, so it adds little parameter-specific meaning beyond the schema.

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 uses a specific verb and resource: 'List invoice/booking line items.' It also names the returned fields and ends with 'GET /line_items,' making clear it is a read/list tool for line items rather than invoices, bookings, or payments.

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 by the resource and the available filters in the schema, but the description does not explicitly say when to use this tool versus siblings such as list_invoices or list_bookings, nor does it state any exclusions.

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