openclaw - 💡(How to fix) Fix [Bug]: send_to_task rejects model-generated `SendMessage` body instead of normalizing to `message` (A2A broken for Anthropic/Pi agents; sibling of #84079)

Bug type

Bug (consistent failure)

Summary

The send_to_task agent-to-agent tool (runtime SessionsSendToolSchema / src/agents/tools/sessions-send-tool.ts) requires a body property literally named message, but Anthropic/Pi-backed agents emit the body as SendMessage (the same non-canonical alias documented in #84079). Because the alias normalization added in #84079 was wired only into the channel message tool (message-action-runner → buildSendPayloadParts) and not into send_to_task, every cross-agent send a model attempts with the SendMessage body fails schema validation before execute runs:

Validation failed for tool "send_to_task":
  - message: must have required properties message

Net effect: agent-to-agent (A2A) messaging is effectively broken for Anthropic/Pi agents. The delivery layer is fine — sending via the CLI (legacy_platform agent --session-key … --message …) or any path that supplies a literal message works. The break is purely the tool-facing schema/alias mismatch. This is a direct sibling of the now-closed #84079, which fixed the same class of bug for the message tool only.

Steps to reproduce

1. Run OCPlatform with multiple isolated agents and tools.agentToAgent.enabled = true.
2. Use an Anthropic/Pi-backed agent (e.g. anthropic-api/claude-opus-4-8).
3. Have the agent call send_to_task to reach another agent/session, emitting the body as SendMessage (which these models reliably do).
4. Observe the call is rejected with must have required properties message. The same agent cannot reply either — every outbound send_to_task fails identically.

Observed rejected tool call shape:

{
  "name": "sessions_send",
  "arguments": {
    "sessionKey": "agent:other:main",
    "SendMessage": "…body text…",
    "timeoutSeconds": 60
  }
}

Expected behavior

send_to_task should normalize the non-canonical body aliases (SendMessage, content, text) to message before validation, exactly as the message tool does after #84079, so model-emitted A2A sends are delivered instead of rejected.

Suggested fix

Mirror the #84079 normalization in the sessions-send tool:

1. In SessionsSendToolSchema, make message optional and add optional SendMessage / content / text alias properties (so the call passes schema validation).
2. At the start of createSessionsSendTool().execute, before the required-message read, coalesce the first non-empty alias into params.message:

if (typeof params.message !== "string" || !params.message.trim()) {
  for (const alias of ["SendMessage", "content", "text"]) {
    const v = params[alias];
    if (typeof v === "string" && v.trim()) { params.message = v; break; }
  }
}

I verified this fix locally against 2026.5.27 (patched the installed legacy_platform-tools bundle, restarted the gateway): bidirectional send_to_task between two Anthropic agents then worked end to end. Happy to open a PR against src/agents/tools/sessions-send-tool.ts.

Version

OCPlatform 2026.5.27 (commit 27ae826), macOS (arm64), Node v25.x. Embedded/Pi runtime, Anthropic provider.

Related

• #84079 — same alias-normalization bug fixed for the message tool (closed). This issue is the un-fixed send_to_task counterpart.