openclaw/docs/concepts/session-tool.md

---
summary: "Agent session tools for listing sessions, fetching history, and sending cross-session messages"
read_when:
  - Adding or modifying session tools
title: "Session Tools"
---

# Session Tools

Goal: small, hard-to-misuse tool set so agents can list sessions, fetch history, and send to another session.

## Tool Names

- `sessions_list`
- `sessions_history`
- `sessions_send`
- `sessions_spawn`

## Key Model

- Main direct chat bucket is always the literal key `"main"` (resolved to the current agent’s main key).
- Group chats use `agent:<agentId>:<channel>:group:<id>` or `agent:<agentId>:<channel>:channel:<id>` (pass the full key).
- Cron jobs use `cron:<job.id>`.
- Hooks use `hook:<uuid>` unless explicitly set.
- Node sessions use `node-<nodeId>` unless explicitly set.

`global` and `unknown` are reserved values and are never listed. If `session.scope = "global"`, we alias it to `main` for all tools so callers never see `global`.

## sessions_list

List sessions as an array of rows.

Parameters:

- `kinds?: string[]` filter: any of `"main" | "group" | "cron" | "hook" | "node" | "other"`
- `limit?: number` max rows (default: server default, clamp e.g. 200)
- `activeMinutes?: number` only sessions updated within N minutes
- `messageLimit?: number` 0 = no messages (default 0); >0 = include last N messages

Behavior:

- `messageLimit > 0` fetches `chat.history` per session and includes the last N messages.
- Tool results are filtered out in list output; use `sessions_history` for tool messages.
- When running in a **sandboxed** agent session, session tools default to **spawned-only visibility** (see below).

Row shape (JSON):

- `key`: session key (string)
- `kind`: `main | group | cron | hook | node | other`
- `channel`: `whatsapp | telegram | discord | signal | imessage | webchat | internal | unknown`
- `displayName` (group display label if available)
- `updatedAt` (ms)
- `sessionId`
- `model`, `contextTokens`, `totalTokens`
- `thinkingLevel`, `verboseLevel`, `systemSent`, `abortedLastRun`
- `sendPolicy` (session override if set)
- `lastChannel`, `lastTo`
- `deliveryContext` (normalized `{ channel, to, accountId }` when available)
- `transcriptPath` (best-effort path derived from store dir + sessionId)
- `messages?` (only when `messageLimit > 0`)

## sessions_history

Fetch transcript for one session.

Parameters:

- `sessionKey` (required; accepts session key or `sessionId` from `sessions_list`)
- `limit?: number` max messages (server clamps)
- `includeTools?: boolean` (default false)

Behavior:

- `includeTools=false` filters `role: "toolResult"` messages.
- Returns messages array in the raw transcript format.
- When given a `sessionId`, OpenClaw resolves it to the corresponding session key (missing ids error).

## Gateway session history and live transcript APIs

Control UI and gateway clients can use the lower level history and live transcript surfaces directly.

HTTP:

- `GET /sessions/{sessionKey}/history`
- Query params: `limit`, `cursor`, `includeTools=1`, `follow=1`
- Unknown sessions return HTTP `404` with `error.type = "not_found"`
- `follow=1` upgrades the response to an SSE stream of transcript updates for that session

WebSocket:

- `sessions.subscribe` subscribes to all session lifecycle and transcript events visible to the client
- `sessions.messages.subscribe { key }` subscribes only to `session.message` events for one session
- `sessions.messages.unsubscribe { key }` removes that targeted transcript subscription
- `session.message` carries appended transcript messages plus live usage metadata when available
- `sessions.changed` emits `phase: "message"` for transcript appends so session lists can refresh counters and previews

## sessions_send

Send a message into another session.

Parameters:

- `sessionKey` (required; accepts session key or `sessionId` from `sessions_list`)
- `message` (required)
- `timeoutSeconds?: number` (default >0; 0 = fire-and-forget)

Behavior:

- `timeoutSeconds = 0`: enqueue and return `{ runId, status: "accepted" }`.
- `timeoutSeconds > 0`: wait up to N seconds for completion, then return `{ runId, status: "ok", reply }`.
- If wait times out: `{ runId, status: "timeout", error }`. Run continues; call `sessions_history` later.
- If the run fails: `{ runId, status: "error", error }`.
- Announce delivery runs after the primary run completes and is best-effort; `status: "ok"` does not guarantee the announce was delivered.
- Waits via gateway `agent.wait` (server-side) so reconnects don't drop the wait.
- Agent-to-agent message context is injected for the primary run.
- Inter-session messages are persisted with `message.provenance.kind = "inter_session"` so transcript readers can distinguish routed agent instructions from external user input.
- After the primary run completes, OpenClaw runs a **reply-back loop**:
  - Round 2+ alternates between requester and target agents.
  - Reply exactly `REPLY_SKIP` to stop the ping‑pong.
  - Max turns is `session.agentToAgent.maxPingPongTurns` (0–5, default 5).
- Once the loop ends, OpenClaw runs the **agent‑to‑agent announce step** (target agent only):
  - Reply exactly `ANNOUNCE_SKIP` to stay silent.
  - Any other reply is sent to the target channel.
  - Announce step includes the original request + round‑1 reply + latest ping‑pong reply.

## Channel Field

- For groups, `channel` is the channel recorded on the session entry.
- For direct chats, `channel` maps from `lastChannel`.
- For cron/hook/node, `channel` is `internal`.
- If missing, `channel` is `unknown`.

## Security / Send Policy

Policy-based blocking by channel/chat type (not per session id).

```json
{
  "session": {
    "sendPolicy": {
      "rules": [
        {
          "match": { "channel": "discord", "chatType": "group" },
          "action": "deny"
        }
      ],
      "default": "allow"
    }
  }
}
```

Runtime override (per session entry):

- `sendPolicy: "allow" | "deny"` (unset = inherit config)
- Settable via `sessions.patch` or owner-only `/send on|off|inherit` (standalone message).

Enforcement points:

- `chat.send` / `agent` (gateway)
- auto-reply delivery logic

## sessions_spawn

Spawn a sub-agent run in an isolated session and announce the result back to the requester chat channel.

Parameters:

- `task` (required)
- `label?` (optional; used for logs/UI)
- `agentId?` (optional; spawn under another agent id if allowed)
- `model?` (optional; overrides the sub-agent model; invalid values error)
- `thinking?` (optional; overrides thinking level for the sub-agent run)
- `runTimeoutSeconds?` (defaults to `agents.defaults.subagents.runTimeoutSeconds` when set, otherwise `0`; when set, aborts the sub-agent run after N seconds)
- `thread?` (default false; request thread-bound routing for this spawn when supported by the channel/plugin)
- `mode?` (`run|session`; defaults to `run`, but defaults to `session` when `thread=true`; `mode="session"` requires `thread=true`)
- `cleanup?` (`delete|keep`, default `keep`)
- `sandbox?` (`inherit|require`, default `inherit`; `require` rejects spawn unless the target child runtime is sandboxed)
- `attachments?` (optional array of inline files; subagent runtime only, ACP rejects). Each entry: `{ name, content, encoding?: "utf8" | "base64", mimeType? }`. Files are materialized into the child workspace at `.openclaw/attachments/<uuid>/`. Returns a receipt with sha256 per file.
- `attachAs?` (optional; `{ mountPath? }` hint reserved for future mount implementations)

Allowlist:

- `agents.list[].subagents.allowAgents`: list of agent ids allowed via `agentId` (`["*"]` to allow any). Default: only the requester agent.
- Sandbox inheritance guard: if the requester session is sandboxed, `sessions_spawn` rejects targets that would run unsandboxed.

Discovery:

- Use `agents_list` to discover which agent ids are allowed for `sessions_spawn`.

Behavior:

- Starts a new `agent:<agentId>:subagent:<uuid>` session with `deliver: false`.
- Sub-agents default to the full tool set **minus session tools** (configurable via `tools.subagents.tools`).
- Sub-agents are not allowed to call `sessions_spawn` (no sub-agent → sub-agent spawning).
- Always non-blocking: returns `{ status: "accepted", runId, childSessionKey }` immediately.
- With `thread=true`, channel plugins can bind delivery/routing to a thread target (Discord support is controlled by `session.threadBindings.*` and `channels.discord.threadBindings.*`).
- After completion, OpenClaw runs a sub-agent **announce step** and posts the result to the requester chat channel.
  - If the assistant final reply is empty, the latest `toolResult` from sub-agent history is included as `Result`.
- Reply exactly `ANNOUNCE_SKIP` during the announce step to stay silent.
- Announce replies are normalized to `Status`/`Result`/`Notes`; `Status` comes from runtime outcome (not model text).
- Sub-agent sessions are auto-archived after `agents.defaults.subagents.archiveAfterMinutes` (default: 60).
- Announce replies include a stats line (runtime, tokens, sessionKey/sessionId, transcript path, and optional cost).

## Sandbox Session Visibility

Session tools can be scoped to reduce cross-session access.

Default behavior:

- `tools.sessions.visibility` defaults to `tree` (current session + spawned subagent sessions).
- For sandboxed sessions, `agents.defaults.sandbox.sessionToolsVisibility` can hard-clamp visibility.

Config:

```json5
{
  tools: {
    sessions: {
      // "self" | "tree" | "agent" | "all"
      // default: "tree"
      visibility: "tree",
    },
  },
  agents: {
    defaults: {
      sandbox: {
        // default: "spawned"
        sessionToolsVisibility: "spawned", // or "all"
      },
    },
  },
}
```

Notes:

- `self`: only the current session key.
- `tree`: current session + sessions spawned by the current session.
- `agent`: any session belonging to the current agent id.
- `all`: any session (cross-agent access still requires `tools.agentToAgent`).
- When a session is sandboxed and `sessionToolsVisibility="spawned"`, OpenClaw clamps visibility to `tree` even if you set `tools.sessions.visibility="all"`.