Prerequisites How progress notifications work Code samples

Receive progress notifications from your AgentCore gateway

Progress notifications allow MCP server targets to report incremental progress on long-running tool calls. When a tool call takes time to complete, the server can send notifications/progress events to keep the client informed about the operation’s status. AgentCore Gateway forwards these notifications from MCP server targets to your client as Server-Sent Events (SSE) chunks.

Prerequisites

To receive progress notifications from your gateway:

Response streaming enabled — Progress notifications are delivered as SSE chunks during an open connection. Set streamingConfiguration.enableResponseStreaming to true in your gateway’s protocolConfiguration.mcp.
MCP server target type — Progress notifications originate from MCP server targets.
Client sends the Accept header — The client must send Accept: application/json, text/event-stream so that the gateway can return a streaming (SSE) response.

How progress notifications work

When a client makes a tools/call request with a progressToken in the request parameters, the MCP server target can send notifications/progress events during execution. The gateway forwards these events to the client as SSE chunks before the final tool result.

Each progress notification includes:

progressToken — Matches the token provided in the original request.
progress — The current progress value (numeric).
total — Optional total value indicating completion target.
message — Optional human-readable description of current status.

Code samples

Example

curl (2025-11-25 and earlier)

Call a tool with a progress token. Set the MCP-Protocol-Version header to a version that your gateway supports.


curl -N -X POST \
  https://mygateway-abcdefghij.gateway.bedrock-agentcore.us-west-2.amazonaws.com/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "MCP-Protocol-Version: 2025-11-25" \
  -d '{
    "jsonrpc": "2.0",
    "id": "tool-call-1",
    "method": "tools/call",
    "params": {
      "name": "analyzeDataset",
      "arguments": {
        "datasetId": "ds-12345"
      },
      "_meta": {
        "progressToken": "progress-1"
      }
    }
}'

The gateway returns an SSE stream with progress notifications followed by the final result:


event: message
data: {"jsonrpc":"2.0","method":"notifications/progress","params":{"progressToken":"progress-1","progress":1,"total":4,"message":"Loading dataset..."}}

event: message
data: {"jsonrpc":"2.0","method":"notifications/progress","params":{"progressToken":"progress-1","progress":2,"total":4,"message":"Running analysis..."}}

event: message
data: {"jsonrpc":"2.0","method":"notifications/progress","params":{"progressToken":"progress-1","progress":3,"total":4,"message":"Generating report..."}}

event: message
data: {"jsonrpc":"2.0","method":"notifications/progress","params":{"progressToken":"progress-1","progress":4,"total":4,"message":"Complete"}}

event: message
data: {"jsonrpc":"2.0","id":"tool-call-1","result":{"content":[{"type":"text","text":"Analysis complete. Found 3 anomalies in dataset ds-12345."}]}}

curl (2026-07-28)

On version 2026-07-28, include the Mcp-Method and Mcp-Name request-metadata headers and the _meta version fields in the body. Keep progressToken in _meta to opt into progress notifications. The MCP-Protocol-Version header must match _meta.io.modelcontextprotocol/protocolVersion. Your gateway’s supportedVersions must include 2026-07-28.


curl -N -X POST \
  https://mygateway-abcdefghij.gateway.bedrock-agentcore.us-west-2.amazonaws.com/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "MCP-Protocol-Version: 2026-07-28" \
  -H "Mcp-Method: tools/call" \
  -H "Mcp-Name: analyzeDataset" \
  -d '{
    "jsonrpc": "2.0",
    "id": "tool-call-1",
    "method": "tools/call",
    "params": {
      "name": "analyzeDataset",
      "arguments": {
        "datasetId": "ds-12345"
      },
      "_meta": {
        "io.modelcontextprotocol/protocolVersion": "2026-07-28",
        "io.modelcontextprotocol/clientInfo": {
          "name": "my-agent",
          "version": "1.0.0"
        },
        "io.modelcontextprotocol/clientCapabilities": {},
        "progressToken": "progress-1"
      }
    }
}'

The gateway returns an SSE stream with progress notifications followed by the final result:


event: message
data: {"jsonrpc":"2.0","method":"notifications/progress","params":{"progressToken":"progress-1","progress":1,"total":4,"message":"Loading dataset..."}}

event: message
data: {"jsonrpc":"2.0","method":"notifications/progress","params":{"progressToken":"progress-1","progress":2,"total":4,"message":"Running analysis..."}}

event: message
data: {"jsonrpc":"2.0","method":"notifications/progress","params":{"progressToken":"progress-1","progress":3,"total":4,"message":"Generating report..."}}

event: message
data: {"jsonrpc":"2.0","method":"notifications/progress","params":{"progressToken":"progress-1","progress":4,"total":4,"message":"Complete"}}

event: message
data: {"jsonrpc":"2.0","id":"tool-call-1","result":{"content":[{"type":"text","text":"Analysis complete. Found 3 anomalies in dataset ds-12345."}]}}

Python requests package (2025-11-25 and earlier)

Set the MCP-Protocol-Version header to a version that your gateway supports.


import requests
import json
import sseclient

gateway_url = "https://mygateway-abcdefghij.gateway.bedrock-agentcore.us-west-2.amazonaws.com/mcp"
headers = {
    "Content-Type": "application/json",
    "Accept": "application/json, text/event-stream",
    "Authorization": "Bearer YOUR_ACCESS_TOKEN",
    "MCP-Protocol-Version": "2025-11-25"
}

# Call tool with progress token (streaming response)
response = requests.post(gateway_url, headers=headers, json={
    "jsonrpc": "2.0",
    "id": "tool-call-1",
    "method": "tools/call",
    "params": {
        "name": "analyzeDataset",
        "arguments": {"datasetId": "ds-12345"},
        "_meta": {"progressToken": "progress-1"}
    }
}, stream=True)

# Process SSE events
client = sseclient.SSEClient(response)
for event in client.events():
    data = json.loads(event.data)
    if data.get("method") == "notifications/progress":
        params = data["params"]
        print(f"Progress: {params['progress']}/{params.get('total', '?')} - {params.get('message', '')}")
    elif "result" in data:
        print(f"Tool result: {data['result']}")
        break

Python requests package (2026-07-28)

On version 2026-07-28, add the MCP-Protocol-Version, Mcp-Method, and Mcp-Name headers, and include the _meta version fields in the request body. Keep progressToken in _meta to opt into progress notifications. Your gateway’s supportedVersions must include 2026-07-28.


import requests
import json
import sseclient

gateway_url = "https://mygateway-abcdefghij.gateway.bedrock-agentcore.us-west-2.amazonaws.com/mcp"
headers = {
    "Content-Type": "application/json",
    "Accept": "application/json, text/event-stream",
    "Authorization": "Bearer YOUR_ACCESS_TOKEN",
    "MCP-Protocol-Version": "2026-07-28",
    "Mcp-Method": "tools/call",
    "Mcp-Name": "analyzeDataset"
}

# Call tool with progress token (streaming response)
response = requests.post(gateway_url, headers=headers, json={
    "jsonrpc": "2.0",
    "id": "tool-call-1",
    "method": "tools/call",
    "params": {
        "name": "analyzeDataset",
        "arguments": {"datasetId": "ds-12345"},
        "_meta": {
            "io.modelcontextprotocol/protocolVersion": "2026-07-28",
            "io.modelcontextprotocol/clientInfo": {"name": "my-agent", "version": "1.0.0"},
            "io.modelcontextprotocol/clientCapabilities": {},
            "progressToken": "progress-1"
        }
    }
}, stream=True)

# Process SSE events
client = sseclient.SSEClient(response)
for event in client.events():
    data = json.loads(event.data)
    if data.get("method") == "notifications/progress":
        params = data["params"]
        print(f"Progress: {params['progress']}/{params.get('total', '?')} - {params.get('message', '')}")
    elif "result" in data:
        print(f"Tool result: {data['result']}")
        break

MCP Client


from mcp import ClientSession
from mcp.client.streamable_http import streamablehttp_client
import asyncio

async def progress_handler(progress_token, progress, total, message=None):
    """Handle progress notifications."""
    print(f"[{progress}/{total}] {message or ''}")

async def use_progress(url, token):
    headers = {"Authorization": f"Bearer {token}"}

    async with streamablehttp_client(url=url, headers=headers) as (
        read_stream, write_stream, _
    ):
        async with ClientSession(
            read_stream, write_stream,
            progress_handler=progress_handler
        ) as session:
            await session.initialize()

            # Call tool with progress token - notifications handled by callback
            result = await session.call_tool(
                name="analyzeDataset",
                arguments={"datasetId": "ds-12345"}
            )
            print(f"Tool result: {result}")
            return result

asyncio.run(use_progress(
    url="https://mygateway-abcdefghij.gateway.bedrock-agentcore.us-west-2.amazonaws.com/mcp",
    token="YOUR_ACCESS_TOKEN"
))

Strands MCP Client


from mcp.client.streamable_http import streamablehttp_client
from strands import Agent
from strands.tools.mcp import MCPClient

mcp_url = "https://mygateway-abcdefghij.gateway.bedrock-agentcore.us-west-2.amazonaws.com/mcp"
access_token = "YOUR_ACCESS_TOKEN"

mcp_client = MCPClient(
    lambda: streamablehttp_client(
        mcp_url, headers={"Authorization": f"Bearer {access_token}"}
    )
)

# Strands handles streaming and progress notifications automatically
with mcp_client:
    agent = Agent(tools=mcp_client.list_tools_sync())
    response = agent("Analyze dataset ds-12345")
    print(response)

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