# log_action defaults

> Exactly what log_action does to the stage and the follow-up time when you leave fields out.

URL: https://mcp-docs.opennomos.com/docs/growth-loop/log-action

[`log_action`](https://mcp-docs.opennomos.com/docs/tools/growth/log_action.md) records something that was done or observed. Only `action.summary` is required. This page spells out what happens to the rest.

## Which opportunity

- `opportunity_id`: that opportunity (must belong to the project).
- `url`: the opportunity with that normalised URL; **an unknown URL is tracked automatically** (use `title` to name it).
- Neither: the action is recorded alone, with no opportunity.

## Stage

| You pass | Result |
| --- | --- |
| `stage` omitted | The stage stays. The server **never infers** a stage from the action. |
| `stage` equal to the current one | No stage change. |
| `stage` different | Stage changes and a `stage_changed` event is recorded. |

## Follow-up time

| Situation | Result |
| --- | --- |
| `next_followup` given (`{"in_days": 3}`, `{"at": "…"}` or an ISO time) | Set to that. |
| `next_followup: null` | Cleared. |
| Omitted, **and the stage changed** | Set from the new stage: `contacted` +3 days, `replied` +2 days, `willing_to_talk` +2 days; `converted` and `dropped` clear it. `discovered` has no default and leaves the time as it was. |
| Omitted, **and the stage did not change** | **Left exactly as it was.** |

The last row matters. Logging a second action on an opportunity that is already past its follow-up time does not push the time forward, so it stays in the briefing's `today` as `followup_due` until you set a new `next_followup`, pass `null`, or change the stage. The response returns `opportunity.next_followup_at`, so you can confirm the value without a second call.

`track` on an existing opportunity behaves the same way for `next_followup`: omitted means unchanged.

## Other fields

| Field | Behaviour |
| --- | --- |
| `experiment_id` | Attaches the action to the experiment, and attaches the opportunity to it if it has none yet. The response includes `experiment_progress`. |
| `link_code` | The short link used in this action, for click attribution. |
| `outcome` | Records a result. Attributed (`direct`) when tied to an opportunity or a link, otherwise `unknown`. If `outcome.type` is `willing_to_talk` and the stage is not, `hints` reminds you to pass the stage. |
| `note` | Extra context; stored on the stage-change or note event. |
| `occurred_at` | When it happened; default now. |
| `idempotency_key` | A repeat with the same key returns the first result with `duplicate: true` and records nothing new. Use it whenever a retry is possible. |

## Do not log

Private message text and personal data. A one-sentence `summary` such as "Sent a DM offering a call" is enough.