list_carrier_subscribers

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

With no annotations, the description carries the full burden. It usefully discloses the return shape ('pagination info and data') and the available filters, but says nothing about read-only nature, auth/permission requirements, or pagination limits/defaults. It adds moderate value but leaves meaningful behavioral gaps.

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 docstring is front-loaded with the purpose, then structured Args/Returns blocks. Every line earns its place, though the Args listing is a fairly mechanical restatement of parameter names.

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 zero-required-param list tool with an output schema already covering returns, the description is largely sufficient: purpose, filters, and return structure are all present. It could say more about read-only behavior and pagination defaults, but nothing critical for correct invocation 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 coverage is only 20% (just 'controller'), yet the description supplies meaning for four of the five params (limit, offset, plan_id, suspended) that the schema leaves undocumented. This is genuine added value over the schema, though the semantics are terse.

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+resource ('List UniFi Carrier Fabric subscribers'), which an agent can distinguish from get_carrier_subscriber and create_carrier_subscriber. It does not explicitly name or differentiate from the nearest list sibling (list_carrier_service_plans), but the resource is unambiguous.

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?

There is no when-to-use guidance, no mention of alternatives (e.g. get_carrier_subscriber for a single record), and no prerequisites or context about when filtering is appropriate. The agent must infer usage entirely from the name.

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