Upload a creative to an ad account from asset URLs

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

Annotations already declare readOnlyHint=false and openWorldHint=true, so the write nature is partly covered; the description nonetheless adds real value by stating 'WRITE' explicitly and disclosing that calls are dry-run by default and require confirm: true to actually execute. It stops short of stating what gets created, whether the operation is reversible, or what permissions/scope the ad account requires.

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?

Two sentences, zero filler, with the action and endpoint front-loaded and the safety-critical dry-run default placed immediately after. Every clause carries information an agent needs before calling.

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 write tool with a nested body and no output schema, the description covers the essentials an agent must know to avoid an unintended real upload, which is the highest-risk aspect here. The remaining omission is what the response contains (e.g. the created creative's ID), but with a create-and-preview flow that is a 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 67%, so the schema carries most of the load for the nested body/assets structure, and the description adds essentially nothing about adAccountId, type, assets, or platformNative. Only the asset-URL source is echoed ('from asset URLs'), which is already visible in the schema. Baseline 3 is appropriate for mid coverage.

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 ('Upload a creative to an ad account') plus the source of content ('from asset URLs') and the backing endpoint (POST /v1/creatives). It is clear what the tool does, but it does nothing to distinguish itself from the near-identically named sibling creativeLibrary_upload, which an agent could easily confuse.

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 never says when to use this tool rather than creativeLibrary_upload, creativeLibrary_file, or creativeLibrary_validate. The only guidance is the dry-run mechanic, which is about how the call behaves, not when to select it. With three plausibly competing upload/create siblings, this gap is material.

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