find_anomaliesRead-onlyCatch a duplicate charge or a price hike before you overlook it
You suspect you've been double-charged, or a subscription quietly got more expensive, but scrolling through months of transactions to find it yourself is tedious and error-prone.
This tool looks for three specific, narrow patterns rather than trying to be a general fraud detector: the same vendor and amount charged more than once within five days of each other, a single charge that's far larger than what's typical for that account, and a recurring charge whose price went up compared to its own history. Each one is reported as an observation, not a verdict — a repeated charge might be a legitimate double order, and a big one might be a planned purchase. The tool tells you what it noticed; you decide what it means.
The price-increase check is the one most worth understanding before you rely on it, because it is deliberately conservative in a way that affects how you should read a clean result. It only flags a price increase when the earlier charges were identical in both amount and description — not close, identical. A subscription that's billed as "NETFLIX.COM" one month and "NETFLIX*STREAMING" the next won't be recognized as the same recurring charge at all, and one that varies by even a single cent between charges before the increase won't register as a pattern to compare against. That means an empty result from this check is not the same as "no price increases happened" — it means none were caught by a detector built to avoid false alarms, at the cost of missing real ones with messy data behind them.
The other two checks — duplicates and unusually large charges — are more reliable simply because their patterns are more mechanical: same amount and vendor close together, or a number that stands out against your own history. Still worth a human glance, but less likely to miss something real the way the price-increase check can.
What this does not do
- The price-increase check only fires on exactly matching amount and description in prior charges — it will miss a subscription that varies by a cent or is billed under a slightly different name each time.
- An empty result is not a clean bill of health, especially for price increases — it means nothing matched the (deliberately strict) patterns this tool looks for, not that nothing unusual happened.
- Reports observations, not conclusions — a flagged duplicate or large charge may turn out to be completely legitimate; this tool doesn't and can't determine intent.
Arguments
| Name | Type | Required | What it is |
|---|---|---|---|
bookId | uuid | Required | — |
from | string | Optional | — |
to | string | Optional | — |
Generated from the tool definition, so it cannot describe arguments the tool does not accept. Unrecognised arguments are rejected rather than ignored.
Common questions
- If this comes back with nothing flagged, does that mean my books are clean?
- Not necessarily, especially regarding price increases. The price-increase check only catches charges that are byte-for-byte identical in amount and description beforehand — an empty result there means nothing matched that narrow pattern, not that no price actually went up.
- Why didn't it catch my subscription that went up in price last month?
- Likely because the description changed slightly between charges, or an earlier charge in the same subscription varied by even a cent. The check requires identical amount and description in every prior instance to be confident it's the same recurring charge before flagging a change.
- What counts as an "unusually large" charge?
- One that stands out against the typical charge size for that account, based on its own history — not a fixed dollar threshold. A book with mostly small transactions will flag a smaller outlier than one that regularly has large expenses.