zdx_list_devices

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

The description explicitly states 'Read-only', consistent with annotations' readOnlyHint=true, and adds useful behavioral details: return row contents, filtering capabilities, and the since HOURS window. It does not mention pagination or rate limits, but the provided context goes beyond the minimal annotation support.

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 compact — a single paragraph with three sentences — and each sentence earns its place: purpose, return structure, filters, and downstream usage. It is front-loaded with the main verb and resource and contains 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 10 parameters, no output schema, and minimal annotation, the description adequately covers the core elements: what is listed, what is returned, filter options, and how to use the results. It omits pagination/offset details and does not mention any ordering or default limits, but these are secondary for a listing tool with rich annotation support.

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?

With only 10% schema description coverage, the description compensates by enumerating the main filter parameters (email, user IDs, MAC/IP, location/department/geo, since). It adds meaning such as interpreting `since` as an 'HOURS window.' However, it does not describe offset or give format details for the filters, so it is informative but not exhaustive.

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 'List active ZDX devices', a specific verb and resource that clearly identifies the tool's function. It further defines the output as 'one identifying row per device (id, hostname, owning user)', which distinguishes it from device-related siblings like zdx_get_device and zdx_list_departments.

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 specifies usage context by explaining filter options (email, user ID, MAC/IP, location/department/geo, since) and explicitly instructs to 'Use a returned device id with zdx_get_device or the deep-trace / probe tools.' It does not provide an explicit 'when not to use' or name an alternative listing tool, so it falls short of a 5.

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