List segment contacts

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

Annotations already signal read-only and non-destructive behavior, but the description adds crucial behavioral context beyond them: the endpoint is deprecated, always uses the default profile, and cannot access other profiles. This is valuable operational information not present in annotations or schema.

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 front-loaded with the core purpose and well-structured into summary, detail, and deprecation warning. There is minor redundancy between the opening sentence and the following sentence ('Retrieve contacts...' / 'This endpoint allows you to fetch...'), but overall it remains concise and readable.

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 simple deprecated list endpoint with one required parameter and two pagination parameters, the description covers purpose, parameter behavior, limitation, and replacement. It does not mention pagination defaults or response shape, and there is no output schema, but the core calling decision is fully supported.

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 page, per_page, and segmentUuid each described in the schema. The description adds only that a segment is 'identified by its UUID,' which is minimal extra meaning beyond the schema, so the baseline 3 is appropriate.

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 'Retrieve' and the resource 'contacts associated with a specific segment,' and it names the exact replacement endpoint. This makes the tool's purpose obvious and distinguishes it from sibling tools like reach_listProfileSegmentContactsV1.

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 explicitly marks the endpoint as deprecated, explains the limitation ('cannot target a profile... always falls back to the client's default profile'), and provides the exact replacement endpoint. This gives an agent clear when-not-to-use guidance and a direct alternative.

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