get_subscriber_stats

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

No annotations are provided, so the description carries the full burden. It discloses that the tool returns aggregate counts by type and claims efficiency, but it does not explicitly state read-only behavior, error handling, or any side effects. While 'Get' implies read-only, serious safety/behavioral details are absent, leaving a clear gap.

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 two short sentences, both of which add value: the first explains what it does, the second adds efficiency context and distinguishes it from a sibling. It is front-loaded with the core action and resource, with no filler.

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 there is no output schema, the description explains the return value at a high level ('counts broken down by type'), but the use of 'etc.' leaves the exact list of types vague. It also does not clarify whether stats cover all subscribers or any temporal scope, though the absence of parameters implies no filtering. Overall, it is mostly complete for a simple aggregate tool, with minor ambiguities.

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 tool has zero parameters, so the schema is empty and the description adds no parameter-specific meaning. Per the rubric, a zero-parameter tool receives a baseline of 4, and the description does not introduce any false parameter expectations. It implicitly clarifies that no inputs are needed, which is fine.

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 uses a specific verb ('Get') and clearly identifies the resource ('aggregate subscriber statistics'), and distinguishes itself from sibling tools like 'list_subscribers' by emphasizing aggregate counts rather than raw listing. The phrase 'counts broken down by type' further adds precision.

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 an explicit comparison to an alternative ('Much more efficient than listing all subscribers'), suggesting when to prefer this tool for aggregate stats. However, it does not explicitly state when not to use it or name other alternatives (e.g., get_subscriber for individual details), so it stops short of full when/when-not guidance.

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