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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: it discloses the insight flags for audiences Reddit cannot use yet or that are too small to deliver, which tells the agent results can carry warning state, and it names the downstream field the audience_id is consumed by.

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 core purpose and dense with selection-relevant detail, but the middle paragraph enumerates return fields (audience_id, name, type, status, size_range, source) that largely duplicate the output schema. Slightly over-sized, though no sentence is pure 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 read-only, single-optional-parameter listing tool with an output schema and read-only annotations, the description is more than sufficient: it names the account scope, the two audience classes covered, and the caveat insights. Nothing an agent needs to invoke 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?

The single ad_account_id parameter is already 100% documented in the schema, including its default and config fallback, so the description adds no parameter-level meaning. Baseline 3 applies when the schema does the heavy lifting.

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+resource ('Reddit custom and saved audiences of the account, and which ad groups use them') and pins down scope tightly enough to separate it from siblings like get_audience_lists, get_audience_targeting, and search_audience_segments. An agent knows exactly what object it is retrieving without opening the schema.

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 explicit when-to-use / when-not-to-use statement and no sibling is named as an alternative. The one workflow hint – that the returned audience_id feeds custom_audience_ids or excluded_custom_audience_ids on an ad group – is genuinely useful routing information, but it is implied usage rather than a selection rule.

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