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 'Read-only' which is a key behavioral trait, confirming it has no side effects. However, it does not mention any other behavioral aspects such as authentication requirements, rate limits, or whether the response is just a count or includes additional details. Given the tool's simplicity, the single disclosure may be adequate, but it falls short of fully explaining what happens during the call.

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 a single, concise sentence that front-loads the core purpose and includes the read-only trait. There is no wasted wording. Every word contributes meaning, and it is easy for an agent to parse quickly.

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 that there are no parameters, no output schema, and the tool is a simple read-only query, the description is complete. It clearly explains what the tool returns (capacity vs. current usage) and that it is read-only. An agent can invoke it without needing additional context, and the description is sufficient for understanding its behavior.

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, and the schema coverage is 100% (empty schema). The description does not need to explain any parameters because there are none. Per the rubric, a baseline of 4 is appropriate for zero-parameter tools, and the description does not claim anything contradictory.

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 what the tool does: returns the number of agents the user can create (base plan + purchased slots) versus how many they have. It uses a specific verb ('get') and resource ('agent plan limits', implied by the tool name and description). It distinguishes itself from sibling tools like get_agent, list_agents, and get_subscription_limits by focusing on capacity/availability. The purpose 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?

The description gives context by noting it is read-only and implies it is for checking capacity, but it does not explicitly say when to use this tool versus alternatives. There is no mention of situations where one would prefer get_subscription_limits or list_agents, nor any exclusion criteria. The usage is implied but not stated explicitly.

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