Claude Platform Docs

Add Session Resource

beta.sessions.resources.add(strsession_id, ResourceAddParams**kwargs) -> BetaManagedAgentsFileResource
POST/v1/sessions/{session_id}/resources

Add Session Resource

Parameters
session_id: str
file_id: str

ID of a previously uploaded file.

minLength1
maxLength128
type: Literal["file"]
mount_path: Optional[str]

Mount path in the container. Defaults to /mnt/session/uploads/<file_id>.

minLength1
maxLength4096
betas: Optional[List[AnthropicBetaParam]]

Optional header to specify the beta version(s) you want to use.

One of the following:
str
Literal["message-batches-2024-09-24", "prompt-caching-2024-07-31", "computer-use-2024-10-22", 38 more]
One of the following:
"message-batches-2024-09-24"
"prompt-caching-2024-07-31"
"computer-use-2024-10-22"
"computer-use-2025-01-24"
"pdfs-2024-09-25"
"token-counting-2024-11-01"
"token-efficient-tools-2025-02-19"
"output-128k-2025-02-19"
"files-api-2025-04-14"
"mcp-client-2025-04-04"
"mcp-client-2025-11-20"
"dev-full-thinking-2025-05-14"
"interleaved-thinking-2025-05-14"
"code-execution-2025-05-22"
"extended-cache-ttl-2025-04-11"
"context-1m-2025-08-07"
"context-management-2025-06-27"
"model-context-window-exceeded-2025-08-26"
"skills-2025-10-02"
"fast-mode-2026-02-01"
"output-300k-2026-03-24"
"user-profiles-2026-03-24"
"user-profiles-2026-08-18"
"advisor-tool-2026-03-01"
"managed-agents-2026-04-01"
"cache-diagnosis-2026-04-07"
"dreaming-2026-04-21"
"thinking-token-count-2026-05-13"
"server-side-fallback-2026-06-01"
"server-side-fallback-2026-07-01"
"fallback-credit-2026-06-01"
"fallback-credit-2026-07-01"
"agent-memory-2026-07-22"
"mid-conversation-tool-changes-2026-07-01"
"compact-2026-01-12"
"computer-use-2025-11-24"
"mcp-tunnels-2026-06-22"
"structured-outputs-2025-11-13"
"task-budgets-2026-03-13"
"thinking-display-updates-2026-08-18"
"ce-user-management-2026-07-13"
Returns
class BetaManagedAgentsFileResource:
id: str
created_at: datetime

A timestamp in RFC 3339 format

formatdate-time
file_id: str
mount_path: str
type: Literal["file"]
updated_at: datetime

A timestamp in RFC 3339 format

formatdate-time

Add Session Resource

import os
from anthropic import Anthropic

client = Anthropic(
    api_key=os.environ.get(
        "ANTHROPIC_API_KEY"
    ),  # This is the default and can be omitted
)
beta_managed_agents_file_resource = client.beta.sessions.resources.add(
    session_id="sesn_011CZkZAtmR3yMPDzynEDxu7",
    file_id="file_011CNha8iCJcU1wXNR6q4V8w",
    type="file",
)
print(beta_managed_agents_file_resource.id)
{
  "id": "sesrsc_011CZkZBJq5dWxk9fVLNcPht",
  "created_at": "2026-03-15T10:00:00Z",
  "file_id": "file_011CNha8iCJcU1wXNR6q4V8w",
  "mount_path": "/uploads/receipt.pdf",
  "type": "file",
  "updated_at": "2026-03-15T10:00:00Z"
}
Returns Examples
{
  "id": "sesrsc_011CZkZBJq5dWxk9fVLNcPht",
  "created_at": "2026-03-15T10:00:00Z",
  "file_id": "file_011CNha8iCJcU1wXNR6q4V8w",
  "mount_path": "/uploads/receipt.pdf",
  "type": "file",
  "updated_at": "2026-03-15T10:00:00Z"
}