Frameworks and agents · Published 2026-10-21 · Updated 2026-10-21 · AgentiSend
Send email from the OpenAI Agents SDK
AgentiSend mail from the OpenAI Agents SDK goes through one function_tool invoked with on_invoke_tool, and a refusal comes back as code and fix.
To send email from the OpenAI Agents SDK on AgentiSend, register one function_tool that posts to POST /emails and is invoked through on_invoke_tool, returning a refusal as code and fix.
Install
pip install openai-agentsThe agentisend package is standard library only, so pip install agentisend adds no other dependency.
Environment
| Variable | Required | What it is |
|---|---|---|
AGENTISEND_API_KEY | yes | The agent's key, with sending_access and a budget on it. Not your own. |
MAIL_FROM | yes | The From address, on a domain you have verified. |
AGENTISEND_BASE_URL | no | Defaults to https://api.agentisend.com. |
The tool
"""OpenAI Agents SDK — one function tool that posts to POST /emails.
The loop invokes the tool through the SDK's own `on_invoke_tool`, which is
the path a run uses after the model emits a tool call. The first call sends.
The second is a different message, so a key whose budget is one comes back
as agent_budget_exceeded. No model is called.
Install both packages with `pip install agentisend openai-agents`. The suite
runs this file against the SDK checkout; a fresh project uses the released package.
AGENTISEND_API_KEY is the agent's key, with sending_access and a budget.
MAIL_FROM is an address on a domain you have verified.
AGENTISEND_BASE_URL is optional.
"""
from __future__ import annotations
import asyncio
import json
import os
from agents import function_tool
from agents.tool_context import ToolContext
from agentisend import AgentiSend, AgentiSendError, idempotency_key
agentisend = AgentiSend()
TO = "openai-agents@example.com"
UPDATE = {
"to": TO,
"subject": "Ticket 4182 — we are looking into it",
"text": "Someone from support will reply within the hour.",
"purpose": "ticket-4182-update",
}
CLOSED = {
"to": TO,
"subject": "Ticket 4182 — closed",
"text": "The ticket is closed.",
"purpose": "ticket-4182-closed",
}
@function_tool
def send_email(to: str, subject: str, text: str, purpose: str) -> str:
"""Send one email to a person who asked for it.
Returns the message id, or a refusal with a code and a fix. When the fix
says a person decides, stop and report it: calling again will not change
the answer.
"""
try:
sent = agentisend.send_email(
{"from": os.environ["MAIL_FROM"], "to": to, "subject": subject, "text": text},
idempotency=idempotency_key(purpose, to),
)
except AgentiSendError as err:
return json.dumps({"sent": False, "code": err.code, "fix": err.fix})
return json.dumps({"sent": True, "id": sent["id"]})
async def _once(arguments: dict) -> dict:
ctx = ToolContext(
context=None,
tool_name="send_email",
tool_call_id="call_" + arguments["purpose"],
tool_arguments=json.dumps(arguments),
)
raw = await send_email.on_invoke_tool(ctx, json.dumps(arguments))
parsed = json.loads(raw)
if not isinstance(parsed, dict):
raise RuntimeError(f"tool returned {raw!r}")
return parsed
def run() -> None:
"""Two tool calls through the SDK, then stop on the refusal."""
async def loop() -> None:
for call in (UPDATE, CLOSED):
result = await _once(call)
print(json.dumps(result))
if result.get("sent") is False:
return
asyncio.run(loop())
if __name__ == "__main__":
run()function_tool publishes send_email. The file does not start a hosted run. It builds a ToolContext and calls on_invoke_tool with the JSON arguments, which is the path a run uses after the model emits a tool call. The function returns a JSON string. When that string is a refusal whose fix says a person decides, stop. The second call in the file is a different message, so a budget of one produces:
{
"error": {
"code": "agent_budget_exceeded",
"message": "This key has used 1 of its 1 recipients for the current monthly period. Each To, CC and BCC recipient counts as one email.",
"fix": "Wait for the period to reset — get_agent_budget and GET /limits/keys/:id both say when. Raising a budget is a person’s decision, made in the console; a key cannot raise its own.",
"docs_url": "https://agentisend.com/what-does-agent-budget-exceeded-mean#agent_budget_exceeded",
"retryable": false
}
}idempotency_key(purpose, to) is what keeps a retry from sending twice. The Python calls that mint the key are in Send email from Python. A full-access key lists arrivals with GET /emails/receiving. This key replies with POST /emails/receiving/{id}/reply. Both are spelled out in Receiving and replying.