---
title: "Send a message in an existing conversation session"
method: POST
path: "/v1/tools/session-message"
tags: ["AI"]
---

# Send a message in an existing conversation session

`POST /v1/tools/session-message`

## Request

- Base URL: `https://archtools.dev`
- URL: `https://archtools.dev/v1/tools/session-message`
- Auth: API key in header `x-api-key`

Credits scale with the session model: 20 base x model multiplier (Sonnet 1x, Opus 2x, Haiku 0.4x). x402-paid calls are served the standard Sonnet-tier model at the flat x402 price.

## Request body

- object
  - `session_id` string, required: Session ID from session-create
  - `message` string, required: User message to send

## Response `200`

AI response within the session context

---

[API](https://skmtc.dev/archtools/apis/arch-tools-api.md) · [All operations](https://skmtc.dev/archtools/apis/arch-tools-api/llms.txt) · [OpenAPI document](https://skmtc.dev/archtools/apis/arch-tools-api/revisions/ed6c1f974033?raw)