Create a profile segment

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

The description adds meaningful behavioral context beyond the annotations: it explains that membership is dynamic and changes as contacts change, and it explicitly promises that creating a segment does not modify any contact. This is useful safety-relevant information for a mutation tool. It does not cover auth, rate limits, or failure modes, but annotations already convey the non-destructive write nature.

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 extremely efficient: an opening statement followed by one densely informative sentence. Every phrase earns its place, with the key side-effect guarantee and dynamic-membership semantics packed into two sentences. There is no fluff, repetition, or irrelevant detail.

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 creation tool with four required parameters and a rich input schema, the description provides enough conceptual grounding to invoke it correctly: it defines what a segment is and clarifies the side-effect boundary. The absence of an output schema means the return value is not described, but the schema and the concise behavioral definition are sufficient for selection and invocation in most agent workflows.

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%, so the schema carries the full parameter documentation burden. The tool description adds no parameter-level meaning beyond the schema, but the schema already provides a rich description for attributes, operators, and logic. This matches the baseline of 3 for fully covered schemas.

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 verb and resource: 'Create a segment in a profile.' It also adds conceptual precision by explaining that a segment is a saved set of conditions rather than a fixed list. However, it does not differentiate itself from the sibling reach_createANewContactSegmentV1, leaving the distinction between profile segments and contact segments implicit.

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 gives no guidance on when to use this tool versus alternatives such as reach_createANewContactSegmentV1, reach_updateAProfileSegmentV1, or reach_previewContactsMatchingConditionsV1. There is no mention of prerequisites, exclusions, or conditions that would make another tool more appropriate.

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