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

With only readOnlyHint in annotations, the description adds substantial behavioral context: shared-agent scoping for `campaigns`/`senders`, `stale` meaning, `classify_running` progress semantics, and `criteria` null = all with automatic tagging. These are traits an agent cannot infer from the annotation alone.

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 summary is front-loaded and the `<returns>` block is organized logically around the response shape. It is dense and lengthy for a list tool, but the verbosity is largely justified by the absence of an output schema.

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?

Despite no output schema, the description documents the return structure in full, including nested `criteria`, `tags`, `campaigns`, `classifiable_campaigns`, and shared-agent caveats. Nothing an agent needs to call and interpret this tool is missing.

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%, and the sole parameter `on_behalf_of` is fully documented in the schema itself. The description adds no parameter-specific syntax or format beyond the schema, so the baseline 3 applies.

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?

States a specific verb and resource ('List the user's segment groups') and defines what a segment group is with concrete examples ('Seniority', 'Role function'). It also distinguishes the tool from downstream rate/people tools by explaining that this is the source of `group_id`.

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 says 'Read this first to get a `group_id` for the rate / people tools,' giving clear context for when to call it. However, it never states when not to use it or names a sibling list tool as an alternative, so it stops short of the 5 criteria.

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