# Reply to a comment

> Markdown version of https://docs.postlake.dev/api/post-comments-by-id-replies . The canonical page for humans.
> PostLake is the social media API for AI agents: https://postlake.dev/llms.txt

`POST /v1/comments/{id}/replies`

Answer a comment someone left, by that comment's id (from GET /v1/posts/{id}/comments). Distinct from publishing: this acts on someone else's content. Free everywhere except X, where a reply is billed as a post.

## Request

Authenticate with a bearer API key. Agents calling over MCP authorise with OAuth instead and never handle the key.

```bash
curl -X POST https://api.postlake.dev/v1/comments/{id}/replies \
  -H "Authorization: Bearer $POSTLAKE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"account":"…","text":"…"}'
```

### Parameters

| Field | Type | Required | What it is |
| --- | --- | --- | --- |
| `id` | string | Yes | In the URL. The comment id |

### Body

| Field | Type | Required | What it is |
| --- | --- | --- | --- |
| `account` | string | Yes | The connected account id (acc_…) replying |
| `text` | string | Yes | The reply |


## Response

Posted (`200`).

| Field | Type | Required | What it is |
| --- | --- | --- | --- |
| `account` | string | No |  |
| `platform` | string | No |  |
| `id` | string | No |  |
| `ok` | boolean | No |  |



### Example

```json
{
  "account": "…",
  "platform": "…",
  "id": "…",
  "ok": false
}
```


## Calling this from an agent

Agents do not call REST. They call tools. Over the hosted MCP server this operation is `read_comments`, and the agent authorises with OAuth so your API key is never pasted into a chat or seen by the model. You control what any one agent may do: which brands it may act for, which networks it may reach, how much a day, and whether it may spend credits bought up front.

## Errors

Every failure uses one shape: a stable `type`, a granular `code`, the field at fault in `param`, and a plain-language `fix`. See https://docs.postlake.dev/errors.md .

Retries are safe: send the same `Idempotency-Key` and a call that already succeeded returns its original result rather than repeating it.

## Common questions

**Can an AI agent do this without the REST API?**

Yes. Over MCP the same job is the read_comments tool. The agent authorises with OAuth, so no API key is pasted into a chat or seen by the model, and the answer comes back in the same normalised shape.

**Is it safe to retry this call?**

Yes. Send the same Idempotency-Key and a call that already succeeded returns its original result instead of repeating the work. That is what makes it safe to hand to an agent that retries on its own.

**What happens when it fails?**

You get one error shape: a stable type, a granular code you can branch on, the offending field in param, and a fix written so an agent can correct itself rather than stop. Full list on Errors and retries.

## Related

- [Like, repost, follow, block or mute](https://docs.postlake.dev/api/post-engagements.md) `POST /v1/engagements`