asset_create_upload

Reserve an Asset and get a short-lived URL to upload the file to. Step one of bringing your own creative in.

Reserves an Asset and returns a short-lived, presigned URL to upload the file to. This is step one of the upload flow; see Bring your own creative for the whole sequence.

Input

Field	Type	Required	Description
`filename`	`string`	yes	The original filename, including extension.

Output

{ assetId, uploadUrl, expiresAt }:

Field	Type	Description
`assetId`	`ast_*`	The reserved Asset id — pass it to `asset_finalize`.
`uploadUrl`	`string`	A presigned `PUT` URL. Send the file bytes here.
`expiresAt`	`number`	Epoch ms when `uploadUrl` stops working.

The agent uploads the bytes itself

Send an HTTP PUT to uploadUrl with the file as the request body and its Content-Type set. The bytes must never pass through the conversation — the agent reads the file and PUTs it from its own runtime.

PUT <uploadUrl>
Content-Type: image/png

<the file bytes>

Once the PUT returns 200, call asset_finalize.

Example

“Add this logo.png to our creative library.”

Claude calls asset_create_upload({ filename: 'logo.png' }), PUTs the file to the returned uploadUrl, then finalizes with the returned assetId.

Errors

The file’s type and size aren’t checked here — nothing is known until the bytes arrive, so rejection happens at asset_finalize.
401 or 403 — see Errors, which every tool shares. This one needs asset:write.

Reference

Reserve an Asset and get a short-lived URL to upload the file to.

You upload the bytes yourself: send an HTTP PUT to the returned uploadUrl with the file as the body and its Content-Type set. The bytes must never pass through this conversation — read the file and PUT it from your own runtime.

This requires your runtime to reach *.r2.cloudflarestorage.com; if network access is restricted, that host must be allowed. Once the PUT succeeds, call asset_finalize.

Input

Argument	Type	Required	Description
`filename`	string	yes	The original filename, including its extension.

Failure codes

A failed call has isError set, and structuredContent.error holds one of these codes. Errors describes the shape of a failed call.

reservation_failed
forbidden
invalid_request
internal_error

Scope

The token must hold asset:write. Auth & scopes lists each scope.

Annotations

A client reads these hints. A hint that the tool does not declare has the default value of the MCP specification.

Writes. The tool can change data.
Destructive. The tool can make a change that you cannot undo. A client can ask you to confirm before it calls the tool.
Not idempotent. A second call with the same arguments can change more.
Closed world. The tool reads and writes the data of AdCrunch only.