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

No annotations, so the description carries the full burden and does most of it: discloses that signals sets spend credits (fresh snapshot bought, price per contact), that people sets are free, that the result appears in My Audiences, and that it does NOT contact anyone. It stops short of stating reversibility or whether a repeat call buys another snapshot.

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?

Front-loaded with the action and return value, then cost semantics, then the negative side-effect, then the call chain. Dense but every clause carries decision-relevant information; the telegraphic phrasing ('Signals sets SPEND CREDITS') aids scanning.

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 single-parameter tool with no output schema and no annotations, the description covers cost, side effects, prerequisite, and the returned audienceId plus what to do with it. Nothing an agent needs in order to call it correctly 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?

One parameter (`id`) at 0% schema coverage. 'from a marketplace set' implies the id is an audience-set id rather than an audience id, but that is inference — the description never explicitly says which object the id identifies, and sibling tools like get_audience vs get_audience_set make that ambiguity real.

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?

Specific verb + resource: 'Creates a campaign-ready audience from a marketplace set and returns its audienceId.' It also distinguishes itself from near-siblings (buy_audience_set, save_audience, prepare_campaign_audience_from_custom) by naming the source object and the output handle.

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?

Explicit sequencing: only after the user approved `preview_launch_audience_set`, then `create_campaign` with the audienceId, then `preview_launch_campaign`. That is a full when-to-call plus the downstream chain, leaving no inference required.

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