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GPT Actions let a ChatGPT Custom GPT call Postsiva tools directly. Each tool is a POST endpoint with a JSON body matching the MCP tool schema. OpenAPI schema: GET https://backend.postsiva.com/openapi/chatgpt-actions.json

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Requirements

  • Pro plan with gpt_app_enabled
  • Connected social accounts in the target workspace
  • Either ChatGPT OAuth (Connect to Postsiva) or a workspace API key
GPT Actions omit web_search_duckduckgo and clear_workspace_chat_history. Everything else matches the MCP tool catalog.

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Authentication

Two supported methods:
MethodWhen to useHeader
OAuth (recommended)End users in ChatGPTAuthorization: Bearer <JWT from Connect to Postsiva>
API keyInternal/testing Custom GPTsX-API-Key: psk_live_YOUR_KEY or Authorization: Bearer psk_live_YOUR_KEY
OAuth flow:
  1. User clicks Connect to Postsiva in ChatGPT
  2. Signs in at https://backend.postsiva.com/auth/oauth/login
  3. Selects a workspace
  4. ChatGPT receives a Bearer JWT scoped to that workspace
Discovery endpoint: GET /.well-known/oauth-protected-resource

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Call a tool

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POST /unified/gpt-actions/{tool_name}

Replace {tool_name} with the exact MCP tool name (snake_case). Base URL 
https://backend.postsiva.com
Headers 
Content-Type: application/json
Authorization: Bearer YOUR_TOKEN_OR_PSK

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Example — list accounts

curl -X POST "https://backend.postsiva.com/unified/gpt-actions/get_accounts" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: psk_live_YOUR_KEY" \
  -d '{}'
Response example 
{
  "success": true,
  "platforms": ["linkedin", "instagram"],
  "profiles": {
    "linkedin": { "name": "Jane Doe", "handle": "jane-doe" },
    "instagram": { "username": "janedoesocial" }
  }
}

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Example — idea to content

curl -X POST "https://backend.postsiva.com/unified/gpt-actions/idea_to_content" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_OAUTH_JWT" \
  -d '{
    "platforms": ["linkedin", "threads"],
    "idea": "Why async standups beat daily video calls",
    "user_requirements": "Include one stat placeholder"
  }'

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Example — publish

curl -X POST "https://backend.postsiva.com/unified/gpt-actions/publish" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_OAUTH_JWT" \
  -d '{
    "post_type": "text",
    "platforms": ["linkedin"],
    "default_text": "Async standups save 30 minutes per week per engineer.",
    "draft": false
  }'

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Available tools

ToolDescription
get_accountsList connected platforms or one profile
get_queued_postsScheduled posts and drafts
get_user_postsRecent posts per platform
get_unified_analyticsStored cross-platform analytics
get_commentsComments on recent posts
reply_to_commentReply to a comment
manage_platform_connectionOAuth connect URL or disconnect
idea_to_contentTopic → per-platform copy
content_to_imageCopy → generated images
media_to_contentImage/video URL → captions
analyze_mediaDescribe image or video URL
publishPublish, draft, or schedule
disconnect_gpt_connectorRevoke ChatGPT OAuth session
Tool bodies match MCP arguments exactly. Import the OpenAPI schema for full JSON Schema per operation.

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OpenAPI schema

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GET /openapi/chatgpt-actions.json

Public, no auth required. Import this URL when creating a Custom GPT: 
https://backend.postsiva.com/openapi/chatgpt-actions.json
The schema includes:
  • OpenAPI 3.1.0
  • One POST path per tool under /unified/gpt-actions/{operationId}
  • Request body schemas from Pydantic tool inputs
  • BearerAuth security scheme (OAuth JWT or psk_live_ key)
  • x-openai-action-timeout: 120 (seconds)
curl "https://backend.postsiva.com/openapi/chatgpt-actions.json"

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Disconnect ChatGPT connector

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POST /unified/gpt-actions/disconnect_gpt_connector

Revokes the ChatGPT OAuth Bearer token so the next Action call returns 401 until the user reconnects.
  • Does not unlink social platforms (use manage_platform_connection with action=disconnect for that)
  • No-op success when authenticated with an API key (nothing to revoke)
Request body: {} (empty JSON object) 
curl -X POST "https://backend.postsiva.com/unified/gpt-actions/disconnect_gpt_connector" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_OAUTH_JWT" \
  -d '{}'
Response example (OAuth revoked) 
{
  "success": true,
  "revoked_oauth_token": true,
  "detail": "Connector session revoked. Reconnect to Postsiva in ChatGPT on your next request."
}
Response example (API key auth) 
{
  "success": true,
  "revoked_oauth_token": false,
  "detail": "No OAuth Bearer token was revoked (e.g. you use an API key, or token was invalid). Social accounts in Postsiva are unchanged; use disconnect_social_platform to unlink a network."
}

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REST vs MCP vs GPT Actions

FeatureMCPGPT Actions
TransportStreamable HTTP MCPOpenAPI REST
Web searchYes (web_search_duckduckgo)No
Clear chat historyNoNo
AuthAPI key onlyOAuth or API key
TimeoutClient-defined120s (OpenAPI hint)

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Errors

StatusMeaning
401Missing auth or revoked OAuth — user must reconnect in ChatGPT
402 / plan messagegpt_app_enabled not on current plan
422Invalid JSON body or schema validation failure
200 with success: falseTool-level error inside JSON payload

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Setup guide

See ChatGPT Custom GPT setup for step-by-step Custom GPT configuration, OAuth URLs, and privacy instructions.

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Next

ChatGPT setup

Custom GPT walkthrough

MCP tools

Full tool reference

Plans

Pro plan requirements