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

Beyond the annotations (destructiveHint=true, idempotentHint=false), the description discloses the cost model — no destination surcharge but base/field delivery usage still applies — and the 'creator' scope requirement, which the annotations never convey. It also states the response shape (delivery_id, status, cost, download_urls[] once completed), so an agent knows completion is asynchronous.

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?

Six short sentences, front-loaded with the action and immediately followed by the two hard constraints (partner unavailability, the quote-first prerequisite). Every sentence carries operational information — pricing, parameter exclusivity, return values, scope — with 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 mutating, charge-incurring, open-world delivery call, the description covers prerequisites, cost behavior, scope, parameter exclusivity, and completion semantics. An output schema exists, yet the brief return summary still helps an agent plan a wait_for_delivery follow-up; nothing essential is missing.

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%, so the baseline is 3; the description adds genuine meaning with the template_id/field_list mutual-exclusion rule that the schema does not state. It does not explain output_format, include_unmatched, or output_compression behavior, leaving those to the (already thorough) schema text.

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 opens with a specific verb and resource ('Deliver an audience as a download') and constrains the destination, so an agent knows exactly what the call produces. It does not explicitly contrast with the close sibling deliver_file_match or list_deliveries, but the audience-scoped, download-only framing still makes the target operation 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?

It gives explicit sequencing ('Call quote_delivery first: pricing depends on...') and an explicit parameter rule ('Supply template_id OR field_list — not both'). It also names when the tool will fail for reasons outside the caller's control (LiveRamp and Narrative unavailable until partner push confirms egress), which is exactly the kind of precondition an agent cannot infer.

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