add_members_to_segment

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

Discloses authentication method, concurrency limit (max 10), and modes (read-only, dry-run). Also notes that members must already exist and provides error handling details.

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?

Well-structured: purpose, constraints, auth/concurrency, args section with each parameter, and return format. Every sentence adds value 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?

Given no annotations and output schema exists, description covers all necessary context for a batch add tool: prerequisites, behavior, error handling, and return values.

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?

With 0% schema coverage, description compensates fully by explaining each parameter: list_id format, segment_id format, emails as comma-separated string, and where to obtain IDs.

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?

Clearly states 'Add members to a static segment or tag by email address' and specifies it only works on static segments, distinguishing it from sibling tools like tag_member.

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 states when to use (static segments only) and when not (dynamic segments), and provides an alternative ('Use tag_member for single-member tag management').

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