Pass source reddit for a community 0-100 series, or type Reddit Hot Posts for the live title board. The two strings are not interchangeable.
Live data as of 2026-09-10
A reddit vs Reddit Hot Posts comparison on Trends MCP is two different tools. Source reddit on get_growth or get_time_series returns a 0-100 series for one community name, with a volume field when the pipeline has it. Type Reddit Hot Posts on get_top_trends returns ranked post titles and takes no keyword. From the September 10, 2026 pull (as_of 2026-09-10T06:01:34 UTC), rank 1 was Huh, who would've thought, and that title returned HTTP 404 no_data on source reddit. A TIL title at rank 19 missed the same way. askreddit closed at index 56.0 and volume 8,963 on recent_date 2026-09-09. Omit percent_growth and reddit growth defaults to 12M, which then fails because the series is 27 daily points. Mixing the two strings is a 400.
The September 10, 2026 board is the split that still matters next month: live rank is a title list, not a community-volume ranking, and Hot Posts titles have no keyword series. Omitting limit returned limit 25, count 25, offset 0, as_of_ts 2026-09-10T06:01:34.423909+00:00. Rank 1 was Huh, who would've thought. Rank 2 was LINNY SURVIVED HIS GUN SHOT SURGERY! Rank 4 named Mamdani. Follow-up get_growth calls on source reddit used recent_date 2026-09-09, one day behind the board stamp:
| Token | Kind | 30D index | 30D volume | 30D change |
|---|---|---|---|---|
| Huh, who would've thought | rank 1 title | no_data | no_data | HTTP 404 |
| rank 19 TIL title | rank 19 title | no_data | no_data | HTTP 404 |
| askreddit | community | 56.0 from 100.0 | 8,963 from 12,327 | -44.0% |
| todayilearned | community | 29.5 from 60.3 | 1,343 from 1,691 | -51.08% |
| news | community | 6.5 from 100.0 | 915 from 2,764 | -93.5% |
| worldnews | community | 45.4 from 3.0 | 1,623 from 1,173 | +1413.33% |
TIL titles at ranks 19 and 23 are discovery strings, not community names. They do not map to todayilearned. Paste a title into source reddit and the handler returns no_data. The community table is the series that exists.
worldnews shows why the index and the volume field have to be read together. The 30D index jumped 1413.33% from a 3.0 baseline, while volume only rose 38.36% (1,623 from 1,173). news sat at index 6.5 with volume 915, down 93.5% on the index and 66.9% on volume from a 30D peak of 100.0 / 2,764. askreddit held the largest volume in this set at 8,963, still far below any public subscriber census for that community. Quote both columns. Do not call volume a subscriber total.
sort=rank_change with window=7d and limit 10 still used the 06:01:34 stamp, plus baseline_ts 2026-09-02T22:01:39.980616+00:00, then returned count 0 and an empty data array. The note said the board turned over completely versus the 7d baseline: no item appears in both snapshots. window=1d against baseline_ts 2026-09-09T02:01:42.769561+00:00 also returned count 0, with a different note: no items climbed; everything held or fell. Complete turnover and a no-climber day are not the same miss. offset 25 with limit 5 returned count 0 and empty data. This board did not continue past row 25 on this pull.
Two strings, two tools. REST uses mode get_growth or get_top_trends. MCP uses the matching tool names. The live board page is the Reddit Hot Posts API. Community windows live on the reddit subreddit growth API. Window defaults live on get_growth. Pagination and limit are documented with get_top_trends.
{"mode": "get_top_trends", "type": "Reddit Hot Posts"}
{"mode": "get_growth", "source": "reddit", "keyword": "askreddit", "percent_growth": ["7D", "14D", "30D", "1M"]}
{"mode": "get_time_series", "source": "reddit", "keyword": "askreddit"}
{"mode": "get_growth", "source": "reddit, google search", "keyword": "askreddit", "percent_growth": ["30D"]}
The MCP equivalents are get_top_trends(type="Reddit Hot Posts"), get_growth(keyword="askreddit", source="reddit", percent_growth=["7D", "14D", "30D", "1M"]), and get_time_series(keyword="askreddit", source="reddit"). REST top_trends with type Reddit Hot Posts and limit 3 on September 10, 2026 returned as_of_ts 2026-09-10T06:01:34.423909+00:00, with count 3: Huh, who would've thought; LINNY SURVIVED HIS GUN SHOT SURGERY!; Meant to be together. That stamp matched the omitted-limit MCP pull.
7D matched 1W exactly on askreddit: index 56.0 versus 21.4, growth +161.68%, volume 8,963 from 6,321, volume_growth +41.8%. 14D matched 2W: +146.7% from 22.7 / 6,417. 30D matched 1M: -44.0% from 100.0 / 12,327. Extra windows still sit on one source-plus-keyword request.
The comma-separated askreddit call returned sources_requested ["reddit", "google search"], sources_successful 2, and trend_analysis.uptrend_ratio 0/2. Reddit 30D was -44.0% with 27 daily points and recent_date 2026-09-09. Google Search 30D was -7.14% (28.0 to 26.0) on recent_date 2026-09-05 with 261 weekly points and no volume field in that row. volume_weighted_growth printed -27.29 from reddit alone, with weight_coverage 1/2 sources. Same preset, different grain, different close dates. Read source_results before joining those percentages.
get_time_series for askreddit on reddit returned 27 daily rows from 2026-08-13 (index 100.0, volume 12,327) to 2026-09-09 (index 56.0, volume 8,963). Each row carried date, value, volume, keyword, and datatype reddit. There was no 2026-08-27 row. On 2026-09-05 the index printed 0.0 while volume stayed 4,686. The 0-100 column is not a rescaled volume. llms.txt still describes about 5 years of weekly history. This source, on this pull, was a 27-day daily strip.
todayilearned 7D printed index 29.5 from 92.4 (-68.07%) with volume 1,343 from 2,054. Two TIL titles sat on the Hot Posts board that morning. The community series was already down over 7 days. A title list and a community curve are not a cross-check unless the keyword is the community name.
get_top_trends with type reddit returned HTTP 400, error invalid_request, message Unknown type 'reddit', plus 24 valid feed labels that include Reddit Hot Posts and Reddit World News. type Reddit failed with the same error. get_growth with source Reddit Hot Posts and keyword askreddit returned HTTP 400, error invalid_source, message 'reddit hot posts' is not a valid source., plus 16 valid sources: google search, google images, google news, google shopping, youtube, wikipedia, tiktok, reddit, amazon, news sentiment, news volume, app downloads, app rankings, steam, npm, python, all. The handler lowercased the rejected source. It did not map it to reddit.
The inverse fold exists on the feed name. type reddit hot posts on get_top_trends returned HTTP 200 and echoed type Reddit Hot Posts, with the same 25 titles as the canonical label and as_of_ts 2026-09-10T06:01:34.423909+00:00. llms.txt still describes feed labels as case-sensitive. The live handler accepted this lowercase Reddit string on September 10, 2026. Prefer the canonical Reddit Hot Posts spelling in stored configs.
get_time_series on reddit, google search returned invalid_source too, with the 16 names and no all. Multi-source strings belong on get_growth only.
REST omitting type is a different 400. POST https://api.trendsmcp.ai/api with mode get_top_trends and limit 5, no type, returned HTTP 200 with envelope statusCode 400, error invalid_request, message The 'type' parameter is required, then the same 24-name list. llms.txt still names that miss missing_parameter. Read statusCode inside the JSON, not only the HTTP line.
country GB with limit 5 on Reddit Hot Posts returned HTTP 400, error invalid_request, message that country is only supported for Google Trends, Google Trends by Category, TikTok Trending Hashtags, TikTok Trending Hashtags by Category, X (Twitter) Trending, and YouTube Trending. Reddit Hot Posts is not on that list. Omit country on this feed.
Omit percent_growth on askreddit and the handler returned HTTP 400, error growth_calculation_failed, message No growth window could be calculated., with a single 12M row of date_out_of_range. data_start was 2026-08-13. data_end was 2026-09-09. The default window is 12M. That default ran. The call did not fall back to a shorter preset. Pass 7D, 14D, or 30D on this source until the history lengthens.
3M and YTD failed with the same date_out_of_range on askreddit. todayilearned, news, wallstreetbets, funny, and movies printed data_start 2026-08-12 or 2026-08-13 on those long windows. Window length is per community, not a global reddit calendar. llms.txt still lists 7D among standard growth windows and still presents 12M as the omit default. Short windows work here. The omit default does not.
Other communities on the same recent_date confirm the grain. wallstreetbets sat at index 2.4 and volume 1,189, down 92.23% over 7 days from 30.9 / 2,136 and down 97.6% over 30 days from 100.0 / 4,438. funny sat at 18.1 / 1,049, down 21.98% over 7 days and 76.49% over 30 days. pics sat at 46.5 / 917, down 11.43% over 7 days and up 13.69% over 30 days. movies sat at 19.3 / 1,348, down 71.82% over 7 days. Those names are valid keywords. The rank 1 title is not.
get_top_trends MCP pricing is 1 credit per 10 requested rows, max 10 credits per call. REST counts 1 request per call. Free boards still cap at the top 10. The 25-row pulls on this page are the paid default, which is also what the handler returns when limit is omitted on a paid key. The keyword-window follow-up is the reddit subreddit growth API. This split stays inside one platform: a short daily community series versus live post rank.
FAQ