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

Annotations already declare readOnlyHint=true, so the description correctly focuses on additional behavioral context: it clarifies that membership is derived from a filter rather than a stored member list. This is meaningful beyond the annotation and helps the agent reason about the returned data.

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?

Three compact sentences with no filler. The core action is front-loaded, the conceptual clarification follows, and the sibling alternative is given at the end without 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?

For a single-parameter, read-only tool with no output schema, the description covers what the tool returns, why an agent would use it, and how it differs from the closest sibling. Nothing essential for correct invocation 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?

Schema coverage is 100% and the single parameter audience_id is already described as 'The audience ID'. The description merely echoes 'by ID' without adding new semantic detail, so the schema carries the load and a baseline score of 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?

States a specific verb+resource ('Get one audience by ID') and adds the unique distinguishing detail that it returns the membership filter, not a member list. This clearly separates it from siblings like list_audiences and list_audience_members.

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?

Explicitly explains when to use this tool: to explain why someone is or is not in an audience, because the filter is the rule. It also names the alternative, list_audience_members, for the related but different need of seeing who currently matches.

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