initialize

curl -X POST "https://open.bigmodel.cn/api/mcp/web_search_prime/mcp"
-H "Authorization: Bearer <key>"
-H "Content-Type: application/json"
-H "Accept: application/json, text/event-stream"
-d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{},"clientInfo":{"name" :"test","version":"1.0"}}}' 4. Without Accept header → Java stacktrace error ❌ Environment

• mcporter: 0.9.0
• Node: v22.22.2
• OS: Linux (WSL2)
• Target: 智谱 BigModel MCP (Streamable HTTP transport)

Expected behavior

mcporter should include Accept: application/json, text/event-stream on all Streamable HTTP POST requests, and manage Mcp-Session-Id across the session lifecycle per the MCP spec.

Actual behavior

mcporter sends POST requests without the required Accept header, causing the server to return a Java stacktrace error instead of MCP responses. All tool calls return "[]" (empty string) with no error message surfaced to the user. The Accept header and session management gaps make mcporter incompatible with any MCP server that strictly validates the Streamable HTTP transport protocol.

OpenClaw version

OpenClaw 2026.4.23 (a979721)

Operating system

Linux (WSL2, Ubuntu, kernel 6.6.87.2-microsoft-standard-WSL2, x64)

Install method

No response

Model

zai/glm-5.1 (智谱 BigModel)

Provider / routing chain

zai/glm-5.1 (智谱 BigModel)

Additional provider/model setup details

No response

Logs, screenshots, and evidence

TL;DR

To fix the issue, mcporter needs to include the Accept: application/json, text/event-stream header in all Streamable HTTP POST requests and manage the Mcp-Session-Id across the session lifecycle.

Guidance

• Add the Accept header with the required values to the POST requests sent by mcporter to ensure compatibility with MCP servers that strictly enforce the Streamable HTTP transport spec.
• Implement session management in mcporter to propagate the Mcp-Session-Id header in subsequent requests after initialization.
• Verify the fix by testing mcporter with the 智谱 MCP server using the provided configuration and checking for the presence of the Accept header and Mcp-Session-Id in the requests.
• Use tools like curl to test the API and compare the results with mcporter to identify any discrepancies.

Example

// Example of a POST request with the required Accept header
{
  "method": "POST",
  "url": "https://open.bigmodel.cn/api/mcp/web_search_prime/mcp",
  "headers": {
    "Authorization": "Bearer <valid-api-key>",
    "Content-Type": "application/json",
    "Accept": "application/json, text/event-stream"
  },
  "data": {
    "jsonrpc": "2.0",
    "id": 1,
    "method": "initialize",
    "params": {
      "protocolVersion": "2025-03-26",
      "capabilities": {},
      "clientInfo": {
        "name": "test",
        "version": "1.0"
      }
    }
  }
}

Notes

The provided information suggests that the issue is specific to the mcporter implementation and its compatibility with the Streamable HTTP transport spec. The fix should focus on adding the required Accept header and implementing session management.

Recommendation

Apply a workaround by modifying mcporter