list_users

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

With no annotations, the description carries full behavioral burden. It discloses that the tool returns a single page of up to MAX_PER_PAGE users with no pagination support, which is a key behavioral trait. It also details the return format (JSON string with users[] and each user's fields). It does not mention side effects, but as a read-only listing operation that is largely self-evident from the verb 'list'.

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 well-organized with an initial purpose sentence, then an Args section and a Returns section. The first sentence front-loads the purpose and the pagination limitation. While it is a bit detailed, each piece of information (parameter semantics, return structure, field types) earns its place. No wasted words.

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?

The tool is simple with one optional parameter. The description covers the parameter, the return format (including all fields and their types), and the pagination limitation. It also explains the auto-resolution behavior. For its complexity, nothing an agent needs to call it correctly 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?

The input schema provides only account_id with no description (0% schema coverage). The description compensates fully: it explains what account_id is ('CallRail account ID') and that it auto-resolves if omitted, which is crucial for the agent to know the parameter is optional and how it behaves. This is a clear value-add beyond the schema.

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 opens with a specific verb and resource: 'List all users on the account.' This clearly distinguishes it from siblings like get_user (single user) and other list_* tools by resource. It also adds scope detail (single page, no pagination) which further clarifies its function.

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 a usage context by stating 'adequate for small and medium agency accounts' and notes the lack of pagination, implying it is not suitable for large accounts. However, it does not explicitly name alternatives (e.g., get_user for a single user) or state when to use this tool versus others. The guidance is implied rather than explicit.

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