get_growth can compare one keyword on several platforms in one POST. Set source to a comma-separated list of MCP names. The inner object then includes sources_requested, source_results, trend_analysis, and volume_weighted_growth. The HTTP call is still POST https://api.trendsapi.ai/api. Parse the string body. Single-source shape is on get_growth.
The comma-separated source field
POST https://api.trendsapi.ai/api
Authorization: Bearer <api_key>
Content-Type: application/json
{"mode":"get_growth","source":"google search, tiktok, youtube","keyword":"air fryer","percent_growth":["12M"]}
Copy each name. google search keeps the space. tiktok is lowercase. Do not send live types such as TikTok Trending Hashtags here.
A 27 Aug 2026 pull with that body set sources_requested to google search, tiktok, and youtube. sources_successful was 3. metadata.mode was multi_sources.
source_results is the compare
Each source_results item has source, status, and results. On that pull, google search returned 12M growth 16.67 (56.0 vs 48.0). youtube returned 36.36 (90.0 vs 66.0). tiktok remapped the term to airfryer and returned date_out_of_range for 12M, with data_start 2026-07-27 and data_end 2026-08-25. The source status was still success.
trend_analysis on that pull counted 2 sources (uptrend_count 2). The TikTok window did not enter the ratio. Read results[].status before averaging.
A source can succeed and still miss a window
Short history is a row error, not a transport 429. Retry with a shorter preset from growth period presets, or drop that source from the list.
The blended number, when volume exists, is volume-weighted growth. Caps stay on pricing.