list_dv360_line_items

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

Annotations already declare read-only, idempotent, non-destructive behavior, so the bar is lower and the description adds real value on top: a 200-result cap, the warning that this returns settings rather than metrics, and the constraint that the filter must be reused across pages. The one gap is that it doesn't explain what page_token returns or how exhaustion is signalled, though the output schema likely covers that.

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?

Three short sentences, purpose front-loaded, caveats after. Efficient with no filler, though the fragment-style phrasing makes the filter/pagination note slightly cryptic.

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 no explanation, and the description covers purpose, pagination, and the metric-vs-settings distinction. But with five parameters at 0% schema coverage and the required advertiser_id unexplained, an agent still lacks enough to invoke confidently without trial and error.

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 carries the full burden, yet it only clarifies the 'filter' parameter (native DV360 syntax, reused across pages). The required advertiser_id and the account, page_size, and page_token parameters get no explanation at all, leaving half the invocation contract undocumented.

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 ('List DV360 line items settings') and explicitly separates itself from performance-metric tooling, so the agent knows this is a configuration-listing operation, not a reporting one. It does not differentiate itself from the adjacent list_dv360_campaigns / insertion_orders / creatives siblings, so it stops short of a top score.

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 line 'These are not performance metrics' implicitly steers the agent toward the report tools for metrics, and 'use the same filter when requesting the next page' gives concrete pagination guidance. However, no alternative tool is named explicitly and no prerequisites (e.g., needing an advertiser_id from list_dv360_advertisers) are stated.

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