List Segments

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

The description goes beyond the readOnlyHint annotation by detailing return fields ('name, id, created_at') and pagination behavior ('Use pagination (limit, after/before) for large lists'). It also states 'List all segments in the account,' which clarifies scope. This adds meaningful context about what the tool does and how results are returned, complementing the annotation.

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?

The description is well-structured with bolded section headers ('Purpose', 'NOT for', 'Returns', 'When to use'), making it scannable and front-loaded. Every sentence provides actionable information with no redundancy or filler. It is appropriately concise for the tool's complexity.

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 tool's simplicity, the description covers all necessary aspects: purpose, alternatives, return fields, pagination, and trigger phrases. No output schema exists, but the description explicitly states what is returned. It is complete enough for an agent to invoke correctly without additional context.

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 input schema already provides 100% coverage with clear descriptions for all three parameters (after, before, limit), including constraints and defaults. The description only mentions pagination generically without adding new semantic details. With high schema coverage, a baseline of 3 is appropriate; the description adds no significant parameter-level information beyond the schema.

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 clearly states the tool's purpose: 'List all segments in the account.' It uses a specific verb and resource, and explicitly distinguishes from related tools with 'NOT for: Listing contacts inside a segment (use list-contacts with segmentId). Not for listing broadcasts (use list-broadcasts).' This fully clarifies scope and differentiates from siblings.

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 provides explicit usage guidance: 'When to use: User says "show my segments", "what lists do I have?", or before create-contact/create-broadcast when segmentId is unknown.' It also includes clear alternatives in the 'NOT for' section, naming specific sibling tools. This gives an agent definitive criteria for when to select this tool.

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