curl -X POST 'https://api.anthropic.com/v1/sessions/session-id/resources?beta=true' \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H 'anthropic-version: 2023-06-01' \
  -H 'Content-Type: application/json' \
  -d '{
  "type": "file",
  "file_id": "file-id"
}'

# POST /v1/sessions/{session_id}/resources?beta=true (Claude API)
Base URL: https://api.anthropic.com
Auth: x-api-key; Anthropic API key; required.
Status: Beta.
Request formats: application/json.
Last verified: 2026-10-20

> Add Session Resource

## Critical Gotchas
* Authentication uses the `x-api-key` header and requests also require an `anthropic-version` header.
* The official OpenAPI URL is discovered from the SDK repository manifest and must remain under Anthropic's trusted Stainless storage prefix.

## cURL
curl -X POST 'https://api.anthropic.com/v1/sessions/session-id/resources?beta=true' \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H 'anthropic-version: 2023-06-01' \
  -H 'Content-Type: application/json' \
  -d '{
  "type": "file",
  "file_id": "file-id"
}'

## Parameters
| Name | In | Type | Required | Description |
| :--- | :--- | :--- | :--- | :--- |
| session_id | path | string | Yes | Path parameter session_id |
| type | body | string | Yes | Request body field type. |
| file_id | body | string | Yes | ID of a previously uploaded file. |
| mount_path | body | string | No | Mount path in the container. Defaults to `/mnt/session/uploads/<file_id>`. |

## Response example
{"type":"file","id":"sesrsc_011CZkZBJq5dWxk9fVLNcPht"}

---
Need an API key? Get one at https://console.anthropic.com/settings/keys

POST

POST /v1/sessions/{session_id}/resources?beta=true — Claude API

Beta

Anthropic API key (required); https://api.anthropic.com

Claude API

Add Session Resource

Base URL: https://api.anthropic.com
Auth: x-api-key: <ANTHROPIC_API_KEY>
Last verified: 2026-10-20 · upstream hash matched

Actions Try in browser→

Agents: curl -H "Accept: text/markdown" this URL
→ 244 tokens · Vary: Accept

Critical gotchas

Authentication uses the x-api-key header and requests also require an anthropic-version header.

The official OpenAPI URL is discovered from the SDK repository manifest and must remain under Anthropic's trusted Stainless storage prefix.

cURL

curl -X POST 'https://api.anthropic.com/v1/sessions/session-id/resources?beta=true' \  -H "x-api-key: $ANTHROPIC_API_KEY" \  -H 'anthropic-version: 2023-06-01' \  -H 'Content-Type: application/json' \  -d '{  "type": "file",  "file_id": "file-id"}'

Parameters

Name	In	Type	Required	Description
session_id	path	string	Yes	Path parameter session_id
type	body	string	Yes	Request body field type.
file_id	body	string	Yes	ID of a previously uploaded file.
mount_path	body	string	No	Mount path in the container. Defaults to `/mnt/session/uploads/<file_id>`.

Response 200 OK

{
  "type": "file",
  "id": "sesrsc_011CZkZBJq5dWxk9fVLNcPht",
  "file_id": "file_011CNha8iCJcU1wXNR6q4V8w",
  "mount_path": "/uploads/receipt.pdf",
  "created_at": "2026-03-15T10:00:00Z",
  "updated_at": "2026-03-15T10:00:00Z"
}

Get a free Claude API key → sponsored

Affiliate link - we may earn a commission, at no extra cost to you.