Dv360.Line Item.Update

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

No annotations are provided, so the description carries the full burden. It does disclose the most important behavioral trait — that mutations are guarded by a preview/confirm-token gate — which is genuinely useful and not derivable from the schema. It stops short of saying what a preview returns, how the token is obtained, whether the update is reversible, or what permissions are required.

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?

A single sentence with zero filler, front-loading the operation and following with the scoping and guard constraints. Nothing could be removed without losing signal.

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?

An output schema exists, so return values need not be explained. For a mutation on a nested free-form payload with no annotations and 0% schema coverage, however, the description should spell out the preview-then-confirm mechanics and permission requirements; those are the gaps an agent would hit on first invocation.

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 0%, so the description must compensate. It does map loosely onto all four parameters: 'by id' implies line_item_id and advertiser_id, 'partial field set' maps to fields, and 'confirm token' maps to confirm. But it adds no format, token origin, or which fields are mutable, leaving the free-form 'fields' object entirely opaque.

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 ('Update a line item by id') and scopes the payload to a 'partial field set', which distinguishes it from a full replace. It does not name the nearest sibling, dv360.line_item.set_status, so an agent must infer that status changes go elsewhere, but the core operation is unambiguous.

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 parenthetical 'guarded: preview + confirm token' hints at a two-step flow, which is implicit usage guidance. However, it never says when to prefer this tool over dv360.line_item.set_status, nor does it explain the precondition sequence (call first without confirm, then re-call with the returned token) an agent must follow.

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