ad_manager_fb_get_custom_audiences

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, so the agent knows this is a safe read. However, the description adds no behavioral context beyond a tautological restatement of the name—no mention of pagination, results scope, or data source behavior. Since annotations cover the safety profile, the description's lack of extra context warrants a 2.

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?

The description is extremely short (3 words), but this is under-specification rather than concise efficiency. It omits essential details and does not earn its place because it conveys almost nothing useful.

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 tool with no output schema, the description should at least indicate what is returned (e.g., a list of audiences) and any important filtering or scoping behaviors. It does none of this, making it inadequate for an agent to call correctly without opening 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?

The input schema provides descriptions for all 4 parameters (100% coverage), including enums for type and source. The description adds no meaning beyond the schema, so per the rubric, baseline 3 is appropriate.

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 'Get custom audiences' states a verb and resource, but it's vague and doesn't distinguish this tool from siblings like ad_manager_fb_get_custom_audience_by_id or ad_manager_fb_get_entity. It fails to specify whether this lists all audiences or a specific one, so an agent can't tell when to use this vs alternatives.

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?

There is no guidance on when to use this tool or what differentiates it from related tools. No mention of alternatives, filtering conditions, or prerequisites, leaving the agent to guess based on the name alone.

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