# Diagnose a Meta CPA spike fast

> Tier: recipe. Operating recipe: real tool sequence, core rules, known traps.

The Meta CPA-spike sequence: events first, frequency second, auction third.

**Intent.** Why Meta CPA jumped: pixel, fatigue, auction, or edits.

## When to use

- CPA jumped beyond noise on meaningful spend.

## When not to use

- No specific contraindication beyond the preconditions below.

## Sources

Required: Meta Ads

## Preconditions

- The account is ticked in the dashboard, confirmed via list_accounts.

## Inputs

- `window`: Analysis window. Default: last 30 days.

## Procedure

1. Split spend vs conversions on the spike. — tools: `meta_get_insights`
2. Check pixel and event volumes. — tools: `meta_get_pixels`
3. Read frequency and CTR trends for fatigue. — tools: `meta_get_insights`
4. Check the activity log for optimisation changes. — tools: `meta_get_ad_activity`

## Decision rules

- **When** Event volume fell account-wide while traffic held → **conclude** Measurement first: the spike may be invisible conversions, not expensive ones.
- **When** Frequency high and CTR decaying on the spenders → **conclude** Fatigue: route to creative-fatigue with the ad sets named.

## Evidence requirements

- Every figure carries its account, metric and window.
- Anything below a readable sample size is reported as unjudged, not as zero.

## Human approval boundary

- The readout changes nothing. Any change it motivates goes through Safe Writes: preview, human confirmation, then apply.

## Failure modes

- iOS and consent modelling shifts move reported CPA without reality moving: check for platform reporting notices in the period.

## Output

- **Readout**: The figures, with windows and accounts named.
- **Flags**: What deserves a deeper skill or a human decision.

## Related

- Skill: [creative-fatigue](https://www.getmcpads.com/skills/creative-fatigue.md)
- Skill: [tracking-audit](https://www.getmcpads.com/skills/tracking-audit.md)