---
title: "Add Session Resource"
method: POST
path: "/v1/sessions/{session_id}/resources?beta=true"
---

# Add Session Resource

`POST /v1/sessions/{session_id}/resources?beta=true`

## Path parameters

- `session_id` string, required

## Headers

- `anthropic-version` string
- `anthropic-beta` string
- `anthropic-workspace-id` string

## Request body

- BetaManagedAgentsAddSessionResourceParams — Mount a file uploaded via the Files API into the session.
  - `type` 'file', required
  - `file_id` string, required — ID of a previously uploaded file.
  - `mount_path` string, nullable — Mount path in the container. Defaults to `/mnt/session/uploads/<file_id>`.

## Response `200`

Successful response (OK)

- BetaManagedAgentsAddSessionResource — The added session resource.
  - `type` 'file', required
  - `id` string, required
  - `file_id` string, required
  - `mount_path` string, required
  - `created_at` string, date-time, required — A timestamp in RFC 3339 format
  - `updated_at` string, date-time, required — A timestamp in RFC 3339 format

## Other responses

- `400` — Invalid argument - The client specified an invalid argument
- `401` — Unauthenticated - The request does not have valid authentication credentials
- `403` — Permission denied - The caller does not have permission to execute the specified operation
- `404` — Not found - Some requested entity was not found
- `408` — Deadline exceeded - The deadline expired before the operation could complete
- `409` — Aborted - The operation was aborted due to concurrency issue
- `412` — Failed precondition - Operation was rejected because the system is not in required state
- `413` — Out of range - Operation was attempted past the valid range
- `429` — Resource exhausted - Some resource has been exhausted (rate limiting)
- `431` — Request header fields too large - Request metadata was too large
- `499` — Cancelled - The operation was cancelled by the client
- `500` — Internal - Internal server error
- `501` — Unimplemented - The operation is not implemented or supported
- `503` — Unavailable - The service is currently unavailable
- `504` — Deadline exceeded - Upstream service did not respond in time

## Changes

- **2026-09-02** `4789294140a2` — 1 info
  - added the new optional `header` request parameter `anthropic-workspace-id`
- **2026-08-17** `d2b230555b7f` — 1 breaking, 2 info
  - the request property `oneOf[#/components/schemas/BetaManagedAgentsFileResourceParams]/mount_path` became not nullable
  - request property `oneOf[#/components/schemas/BetaManagedAgentsFileResourceParams]/mount_path` list-of-types was widened by adding types `null` to media type `application/json`
  - the `oneOf[#/components/schemas/BetaManagedAgentsFileResourceParams]/mount_path` request property's minLength was decreased from `1` to `0`
- **2026-04-08** `69486316563e` — 1 info
  - endpoint added

[Change history](https://skmtc.dev/anthropics/apis/anthropic-api/changes/v1/sessions/:session_id/resources?beta=true/post.md)

---

[API](https://skmtc.dev/anthropics/apis/anthropic-api.md) · [All operations](https://skmtc.dev/anthropics/apis/anthropic-api/llms.txt) · [OpenAPI document](https://skmtc.dev/anthropics/apis/anthropic-api/revisions/1bb7c7a0a4a9?raw)