duo_list_users

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

No annotations are present, so the description carries the full burden. It discloses that the data is PII and classified as isAdmin, which is a useful sensitivity note. However, it does not explicitly state that this is a read-only operation, mention rate limits, pagination behavior beyond schema params, or what happens when no users match. For a list operation, these are minor gaps, but the description adds only the PII context beyond the schema.

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 sentences, front-loaded with the core action ('List users in the Duo account'), and the second sentence efficiently lists return fields and the PII/classification note. Every word earns its place, with no fluff or redundancy.

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 description covers the action, optional filter, and returned fields, which is sufficient for a list endpoint with three optional parameters and no output schema. It lacks explicit guidance on default pagination or rate limits, but the schema already covers limit/offset. The PII note adds important context. Overall, an agent has enough to invoke it correctly, though it could note that it returns all users by default when no username is given.

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% for all three parameters (limit, offset, username). The description's mention of 'optionally filtered by exact username' adds nothing beyond the schema's existing description. Since the schema already documents each parameter's purpose and behavior, the description provides no additional semantic value, placing it at the baseline of 3.

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 the tool lists users in the Duo account, with an optional exact-username filter. It also enumerates the returned metadata fields, which differentiates it from sibling tools like duo_get_user (which fetches a single user) and the various list_* tools for phones, tokens, etc. The verb and resource are specific.

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 implies usage (list users for directory queries) and mentions the optional username filter, but it does not explicitly contrast with alternatives such as duo_get_user for a single user or duo_list_group_users for group-scoped listings. No when-not guidance is provided, though the purpose is clear enough for an agent to infer when to use it.

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