# Complete an MCP local-file upload

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

`PUT /media/upload`

Upload raw file bytes to the short-lived target returned by the MCP upload_media tool when called without a URL. Send the returned upload token as `Authorization: Bearer …` and the exact returned Content-Type. This endpoint does not accept a PostLake API key and is not called until upload_media has prepared a media id and target.

## Request

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

```bash
curl -X PUT https://api.postlake.dev/media/upload \
  -H "Authorization: Bearer $POSTLAKE_API_KEY"
```


## Response

Uploaded; returns the MediaAsset whose id is ready for create_post (`201`).



### Example

```json
"…"
```


## Calling this from an agent

Agents do not call REST. They call tools. Over the hosted MCP server this operation is `upload_media`, 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 upload_media 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.

**How often can I call this?**

Reads are rate limited per account and every response carries X-RateLimit-Remaining and X-RateLimit-Reset. On a 429 the Retry-After header tells you how long to wait.

**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

- [Upload media](https://docs.postlake.dev/api/post-media.md) `POST /v1/media`
- [Upload or prepare several media items](https://docs.postlake.dev/api/post-media-batch.md) `POST /v1/media/batch`