percent_growth is the window field on get_growth. It is an array. Each item is a preset string from the Trends API MCP server, or, on REST only, a {name, recent, baseline} object. Default if the field is omitted: ["12M"]. The call is POST https://api.trendsapi.ai/api. Parse the string body before reading results. When to use the mode itself is on get_growth.
A preset is two dates
The server picks a recent date and a baseline date that match the string, then subtracts on the 0-100 series. growth is that percent. direction is increase, decrease, or flat.
Do not send today 12-m. That is a Google Trends website token. Do not send 7d. That lowercase token is a rank_change lookback on live feeds, documented on rank_change sort. Growth presets use 7D.
POST https://api.trendsapi.ai/api
Authorization: Bearer <api_key>
Content-Type: application/json
{"mode":"get_growth","source":"google search","keyword":"bitcoin","percent_growth":["3M","12M","YTD"]}
Which string to send
Use 7D, 1W, 14D, or 30D when the question is last week or last month versus today. Use 3M, 6M, or 12M for product reviews. Use MTD, QTD, or YTD when the calendar year matters more than a rolling span. Use 5Y only if that source has the history. A source with a short archive returns date_out_of_range on that row and can still succeed on a shorter preset.
The lookup table for every accepted cell is on growth windows. This page is the request rule: array, exact case, one POST.
REST custom pairs
REST accepts:
{"name":"Last Year","recent":"2025-12-31","baseline":"2024-12-31"}
recent is the later date. Mix presets and objects in the same array when the job needs both. The MCP tool does not list the object shape. Use REST for a launch day.
Caps stay on pricing.