add_members_to_segment

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

Annotations already provide basic behavioral hints (non-readonly, non-idempotent, non-destructive). Description adds useful context: prerequisites (members must exist), return format (total_added, total_removed, errors array), and implicit mutability. No contradictions.

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?

Description is structured with a clear paragraph and Args/Returns sections. Though slightly verbose, every sentence adds value. No wasted words.

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?

Covers all essential aspects: purpose, constraints, parameter details, prerequisites, return format, and differentiation from siblings. No output schema exists, but description provides enough return info. Complete for a tool of this complexity.

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 0%, but description compensates well: provides format and source for list_id ('10-char alphanumeric, e.g. 'abc123def4'. Obtain from list_audiences'), segment_id, and emails. The 'account' parameter is not described, but the three required ones are clearly explained.

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 the action ('Add members'), resource ('static segment or tag'), and method ('by email address'). Distinguishes from dynamic segments and mentions sibling tool 'tag_member' for single-member management.

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: 'Only works on static segments (tags), not dynamic segments. Members must already exist in the audience.' Provides alternative: 'Use tag_member for single-member tag management instead.'

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