---
title: "Record one episodic tool-call trace event"
method: POST
path: "/api/agent/sessions/{id}/trace-events"
tags: ["Agent"]
---

# Record one episodic tool-call trace event

`POST /api/agent/sessions/{id}/trace-events`

## Request

- Base URL: `http://localhost:38200`
- URL: `http://localhost:38200/api/agent/sessions/{id}/trace-events`
- Auth: one of:
  - HTTP bearer
  - API key in cookie `token`

T375. Hot path -- the MCP bridge calls this fire-and-forget after every tool invocation.

## Path parameters

- `id` integer, required

## Request body

- object
  - `tool_name` string, required
  - `args` object
  - `result` unknown
  - `duration_ms` integer

## Response `201`

Recorded trace event.

- AgentTraceEvent: T375: one recorded MCP tool-call event (`agent_trace_events` row). `summary`/summary-embedding are populated by a second, best-effort fire-and-forget LLM pass and may be null until it completes (or forever, when the tenant has `external_llm_disabled=true`).
  - `id` integer
  - `tenantId` integer, nullable
  - `sessionId` integer
  - `seq` integer
  - `toolName` string
  - `argsJson` object
  - `resultJson` unknown
  - `durationMs` integer, nullable
  - `summary` string, nullable
  - `createdAt` string, date-time

## Other responses

- `400`: Request body/query failed Zod validation.
- `401`: Missing or invalid credentials.

---

[API](https://skmtc.dev/contextq/apis/contextq-api.md) · [All operations](https://skmtc.dev/contextq/apis/contextq-api/llms.txt) · [OpenAPI document](https://skmtc.dev/contextq/apis/contextq-api/revisions/7afc44056a22?raw)