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

Annotations already declare readOnlyHint=true, and the description adds behavioral context: 'newest first' and 'cursor page' reveal ordering and pagination behavior, plus the API endpoint reference. This goes beyond what annotations provide, though it doesn't detail return formatting.

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 concise sentences: the first front-loads the action and resource with key behavioral details, the second provides the API endpoint. No fluff 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?

Given the simple listing purpose and the rich schema (including references to `next_cursor`), the description plus schema provide sufficient context. It mentions endpoint, ordering, and pagination, though it doesn't explicitly describe the response shape; however, this is partially covered by schema references.

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%, with 'limit' and 'starting_after' fully described in the schema. The description doesn't add parameter-specific semantics beyond the schema, so the baseline of 3 applies.

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 uses a specific verb 'List' with a clear resource 'audiences (contact lists)' and scope 'in the workspace'. It also specifies 'newest first, as a cursor page', which distinguishes it from sibling tools like bird_create_audience and bird_get_audience.

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?

The description clearly implies when to use this tool (listing all audiences) and provides context about ordering and pagination. It doesn't explicitly name alternatives or exclusion criteria, but sibling tools are obviously different in purpose (create/get), making the usage context clear enough.

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