`insufficient_agents`

422 Unprocessable Content Not enough monitoring locations match the requested selection.

When you get it

Not enough monitoring locations match the requested selection. It is always answered with HTTP 422 - one code means one status, so a client may key its handling on either.

Fields it carries

Inside each errors[] entry, beside pointer:

required: What the operation requires the caller to hold or send.
matched: How many items the selection actually matched.
perPool: The per-pool breakdown behind `matched`.

A field is omitted when the server genuinely does not know it - an absent member is never the same as an empty one.

How to fix it

The request was well-formed but a value is not acceptable. The fields above name the offending value and what would be accepted - fix the request and retry.

Shape

{
  "type":   "https://api2.host-tracker.com/problems/insufficient-agents",
  "title":  "Not enough monitoring locations match the requested selection.",
  "status": 422,
  "code":   "insufficient_agents",
  "errors": [
    { "required": …, "matched": …, "perPool": … }
  ]
}