Skip to main content
POST
Send a message

Authorizations

Authorization
string
header
required

Your Reason API key from Settings > API. New keys use reason_; legacy ara_ keys remain accepted. Keys are capability-scoped: run, mcp:read, mcp:write, secrets:read, secrets:write, sessions:read, sessions:debug, knowledge:read, memory:read, memory:write, skills:read, skills:write, repos:read, repos:write, reviews:read, reviews:write, deployment:read, analytics:read, org:read, org:write, attachments:read, attachments:write, guardrails:read, guardrails:write, automations:read, automations:write, agent_auth:read. mcp:write manages MCP server configuration only; it does not authorize remote MCP-tool execution. sessions:debug is privileged: it expands diagnostic session events only for organization owners/admins.

Path Parameters

orgId
string
required

Organization id or slug. Resolve it with GET /v3/self.

sessionId
string
required

The session id.

Body

application/json
message
string
required

Follow-up instruction, at most 2 MiB when UTF-8 encoded.

client_message_id
string

Caller-generated idempotency key. Reusing it for the same Session returns the original accepted turn.

Required string length: 1 - 160
model
string

Optional model id from GET /agent-auth/models to retry this session on. A model override always starts a new continuation run, because a run's model is fixed at its first execution. Omit or use auto to keep the session's current model.

reasoning_effort
enum<string>

Optional reasoning effort override applied to the continuation run.

Available options:
minimal,
low,
medium,
high,
xhigh,
max

Response

Message accepted and delivered or queued for a continuation.

ok
boolean
required
delivery
string
continuation_session_id
string | null

The stable logical Session id after an accepted follow-up. Continue polling this id; Ara may run the turn in a hidden execution Attempt.