Invoke Agent (Sync)

Invoke an agent synchronously. The request blocks until the agent finishes (typically 5–30 seconds) and returns the completed task with the result. For longer-running tasks, use Invoke Agent (Async) or Invoke Agent (Stream).

Path Parameters

agent_id

string

required

Agent ID (UUID)

Request Body

input.text, input.user.id, and input.user.email are required. user_oidc_token is optional for MCP OAuth-backed tools.

input

object

required

Show Input Object

text

string

required

The message or prompt to send to the agent.

user

object

required

Identity of the end user invoking the agent.

Show User Object

string

required

External user ID from your system.

string

required

User email address.

user_oidc_token

string

Optional OIDC token for MCP OAuth-authenticated tools.

string

Thread ID for multi-turn conversations. Pass the id from a previous task’s response to continue the same conversation. The agent will have full context of all prior messages. If omitted, a new thread is created automatically.

disable_attachment_injection

boolean

default:"false"

When true, files passed in input.files are not injected into the LLM context window. The file URLs are still available to the agent’s tools, but the raw content won’t be prepended to the prompt.Use this when:

Files are large (would exceed the model’s context limit)
You want tools to process the files rather than the LLM reading them directly
You’re passing many files and don’t need them all in context

Default (false): file contents are downloaded, extracted, and injected directly into the LLM prompt as context.

think_mode

string

default:"default"

Controls the agent’s reasoning depth. default for standard reasoning, harder for deeper chain-of-thought analysis. Use harder for complex multi-step tasks that benefit from more deliberate planning.

instructions_override

string

Additional instructions appended to the agent’s system prompt for this invocation only. Use this to adjust behavior per-request without changing the agent’s configuration — for example, restricting output format, adding constraints, or changing tone.

expected_output

string

Natural-language description of the desired output (e.g., "A bulleted list of key findings"). Guides the agent’s response style.

Query Parameters

version

string

Agent version to invoke. Defaults to the latest deployed version. Use "draft" to test undeployed changes.

Response

The response is the full task object. The key fields you’ll use:

string

Task/thread ID. Pass this back as id in your next request to continue the conversation.

status

string

completed, failed, error, or stopped

result

string

The agent’s response. If output_format is json, this is a JSON string — parse it with JSON.parse() or jq.

created_at

string

ISO 8601 timestamp when the task was created

finished_at

string

ISO 8601 timestamp when the task completed

Simplest Possible Invoke

curl -X POST "https://api.xpander.ai/v1/agents/<agent-id>/invoke" \
  -H "Content-Type: application/json" \
  -H "x-api-key: <your-api-key>" \
  -d '{"input": {"text": "What is xpander.ai?"}}'

Extract just the result:

curl -s ... | jq -r '.result'

Multi-Turn Conversation

Pass the id from the first response to continue the thread:

# Turn 1
curl -s -X POST "https://api.xpander.ai/v1/agents/<agent-id>/invoke" \
  -H "Content-Type: application/json" \
  -H "x-api-key: <your-api-key>" \
  -d '{"input": {"text": "Hi, my name is David and I work at xpander.ai"}}'

# Response includes: "id": "6525177e-06a1-4063-82fe-37382d2302a5"

# Turn 2 — pass the same id
curl -s -X POST "https://api.xpander.ai/v1/agents/<agent-id>/invoke" \
  -H "Content-Type: application/json" \
  -H "x-api-key: <your-api-key>" \
  -d '{
    "input": {"text": "What is my name and where do I work?"},
    "id": "6525177e-06a1-4063-82fe-37382d2302a5"
  }'

# Agent responds: "Your name is David and you work at xpander.ai."

The agent remembers all previous messages in the thread. Always reuse the same id for follow-ups.

With User Identity

Pass the required user fields so the agent can personalize responses and use identity-aware tools:

curl -s -X POST "https://api.xpander.ai/v1/agents/<agent-id>/invoke" \
  -H "Content-Type: application/json" \
  -H "x-api-key: <your-api-key>" \
  -d '{
    "input": {
      "text": "What is my user ID and email?",
      "user": {
        "id": "user-123",
        "email": "david@xpander.ai"
      }
    }
  }'

{
  "status": "completed",
  "result": "Your user ID is user-123 and your email is david@xpander.ai."
}

The user object is visible to the agent as context. Both id and email are required.

With MCP OAuth

Pass user_oidc_token when the agent uses MCP tools that require OAuth on behalf of the user:

curl -s -X POST "https://api.xpander.ai/v1/agents/<agent-id>/invoke" \
  -H "Content-Type: application/json" \
  -H "x-api-key: <your-api-key>" \
  -d '{
    "input": {
      "text": "Create a calendar event for tomorrow at 10am",
      "user": {
        "id": "user-123",
        "email": "david@xpander.ai"
      }
    },
    "user_oidc_token": "USER_OIDC_TOKEN"
  }'

Processing Files

Files passed in input.files are downloaded and injected directly into the LLM context window by default. This works well for small-to-medium files:

curl -s -X POST "https://api.xpander.ai/v1/agents/<agent-id>/invoke" \
  -H "Content-Type: application/json" \
  -H "x-api-key: <your-api-key>" \
  -d '{
    "input": {
      "text": "What is the abstract of this paper?",
      "files": ["https://assets.xpanderai.io/static/pdf/bitcoin.pdf"]
    }
  }'

{
  "status": "completed",
  "result": "The abstract describes a peer-to-peer electronic cash system that enables direct online payments without financial institutions, solving the double-spending problem through a distributed network using proof-of-work and cryptographic signatures."
}

The 9-page Bitcoin whitepaper (above) processes successfully — its content fits within the model’s context window.

Large Files Fail with Direct Injection

Large files will exceed the model’s context limit and return an error:

# This 185-page PDF will fail — too large for the context window
curl -s -X POST "https://api.xpander.ai/v1/agents/<agent-id>/invoke" \
  -H "Content-Type: application/json" \
  -H "x-api-key: <your-api-key>" \
  -d '{
    "input": {
      "text": "What year was the Apple Macintosh introduced?",
      "files": ["https://assets.xpanderai.io/static/pdf/Introducing_the_Apple_Macintosh_1984.pdf"]
    }
  }'

{
  "status": "error",
  "result": "Error code: 413 - {'error': {'type': 'request_too_large', 'message': 'Request exceeds the maximum size'}}"
}

Files are injected into the LLM context by default. Documents over ~100 pages will typically exceed the model’s token limit. For large documents, use a Knowledge Base instead — add the document to a KB, attach it to the agent, and the agent will search it automatically via RAG.

Disable Context Injection

Set disable_attachment_injection: true to pass the file URL to the agent’s tools without injecting its content into the LLM prompt:

curl -s -X POST "https://api.xpander.ai/v1/agents/<agent-id>/invoke" \
  -H "Content-Type: application/json" \
  -H "x-api-key: <your-api-key>" \
  -d '{
    "input": {
      "text": "Analyze this dataset",
      "files": ["https://example.com/data.csv"]
    },
    "disable_attachment_injection": true
  }'

With this flag, the file URL is available to the agent’s tools but the raw content is not prepended to the prompt. Use this when you want the agent’s tools to process the file rather than the LLM reading it directly.

For very large files (185+ pages), even disable_attachment_injection: true may not be enough — the file can exceed the HTTP request size limit before reaching the LLM. Use a Knowledge Base for production workflows with large documents.

Per-Request Instruction Override

Append instructions for this specific invocation without changing the agent’s configuration:

curl -s -X POST "https://api.xpander.ai/v1/agents/<agent-id>/invoke" \
  -H "Content-Type: application/json" \
  -H "x-api-key: <your-api-key>" \
  -d '{
    "input": {"text": "Tell me about xpander pricing"},
    "title": "Pricing Inquiry",
    "instructions_override": "Always respond in exactly 2 sentences. Never use emojis."
  }'

{
  "status": "completed",
  "title": "Pricing Inquiry",
  "result": "xpander.ai offers two main pricing tiers: a Free plan with 2 serverless agents and 100 AI actions, and an In-House plan at $940/month for up to 10 agents and 200K actions. You can deploy on xpander's managed cloud or your own infrastructure."
}

Structured JSON Output

Request structured output with a JSON Schema:

curl -s -X POST "https://api.xpander.ai/v1/agents/<agent-id>/invoke" \
  -H "Content-Type: application/json" \
  -H "x-api-key: <your-api-key>" \
  -d '{"input": {"text": "Look up Stripe"}}'

To configure output_format and output_schema for structured output, use the Update Agent endpoint or configure it in the dashboard under the Output tab.

Example Response

{
  "id": "6525177e-06a1-4063-82fe-37382d2302a5",
  "agent_id": "<agent-id>",
  "organization_id": "<org-id>",
  "status": "completed",
  "input": {
    "text": "What is xpander.ai in one sentence?",
  },
  "result": "xpander.ai is a full-stack platform for building, deploying, and running autonomous AI agents in production.",
  "source": "api",
  "think_mode": "default",
  "disable_attachment_injection": false,
  "created_at": "2026-02-07T10:15:22.100233Z",
  "started_at": "2026-02-07T10:15:22.500000Z",
  "finished_at": "2026-02-07T10:15:28.997811Z",
  "execution_attempts": 1
}

Overview

REST API - Agents

Agent Workspace

REST API - Tasks

REST API - Knowledge

REST API - Workflows

REST API - Connectors

REST API - Custom Functions

REST API - Toolkits

REST API - Misc

Python SDK - Core Modules

Python SDK - API Reference

CLI Reference

Path Parameters

Request Body

Query Parameters

Response

Simplest Possible Invoke

Multi-Turn Conversation

With User Identity

With MCP OAuth

Processing Files

Large Files Fail with Direct Injection

Disable Context Injection

Per-Request Instruction Override

Structured JSON Output

Example Response

See Also

Authorizations

Path Parameters

Query Parameters

Body

Response

Overview

REST API - Agents

Agent Workspace

REST API - Tasks

REST API - Knowledge

REST API - Workflows

REST API - Connectors

REST API - Custom Functions

REST API - Toolkits

REST API - Misc

Python SDK - Core Modules

Python SDK - API Reference

CLI Reference

​Path Parameters

​Request Body

​Query Parameters

​Response

​Simplest Possible Invoke

​Multi-Turn Conversation

​With User Identity

​With MCP OAuth

​Processing Files

​Large Files Fail with Direct Injection

​Disable Context Injection

​Per-Request Instruction Override

​Structured JSON Output

​Example Response

​See Also

Authorizations

Path Parameters

Query Parameters

Body

Response

Path Parameters

Request Body

Query Parameters

Response

Simplest Possible Invoke

Multi-Turn Conversation

With User Identity

With MCP OAuth

Processing Files

Large Files Fail with Direct Injection

Disable Context Injection

Per-Request Instruction Override

Structured JSON Output

Example Response

See Also