Create custom audience

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

Annotations already declare this is a non-read-only, non-destructive, open-world mutation, so safety is covered. The description adds the post-creation user-population step, which is real behavioral context, but says nothing about permissions, idempotency, or whether a duplicate-named audience is created.

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 short sentences, front-loaded with the core action and followed by the single most useful next-step pointer. No filler or redundancy.

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 annotations covering the safety profile, a fully documented schema, and no output schema, the description covers creation plus the key follow-up step. Minor gap: it never acknowledges the three distinct audience types at a high level, leaving the reader to discover them in the schema.

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% and the nested 'data' description exhaustively documents the three audience types and their config fields, so the schema does the heavy lifting. The description adds no parameter meaning beyond that, which is the expected baseline at full 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 ('Create a custom audience'), which distinguishes it from siblings like create_saved_audience and create_catalog. However it does not explicitly contrast with those siblings, so the reader must rely on the name alone to disambiguate.

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?

Provides one concrete workflow hint: for customer lists, add users afterwards via reddit_ads_update_custom_audience_users. That is genuinely useful, but there is no guidance on when to prefer a custom audience over a saved audience, nor on prerequisites or account scoping.

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