[BUG] MCP HTTP transport polls resources/read at 1 Hz indefinitely, flooding debug log

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When an MCP server is configured with HTTP/SSE transport, Claude Code polls for token data via resources/read approximately once per second for the entire session, regardless of whether any MCP tools are being used. Each poll logs MCP server "<name>": No token data found at DEBUG level.

In a 2h 42m session, this produced 6,485 identical log lines, accounting for 55% of the 1.4 MB debug log. The polling runs continuously from session start to session end with no backoff, deduplication, or suppression.

What Should Happen?

When resources/read returns no token data, Claude Code should log the result once and suppress subsequent identical results, or apply exponential backoff on the poll interval, or stop polling after N consecutive empty results until the next MCP tool call.

Error Messages/Logs

2026-03-14T05:23:23.557Z [DEBUG] MCP server "vhiz": No token data found
2026-03-14T05:23:24.742Z [DEBUG] MCP server "vhiz": No token data found
2026-03-14T05:23:25.922Z [DEBUG] MCP server "vhiz": No token data found
2026-03-14T05:23:27.086Z [DEBUG] MCP server "vhiz": No token data found
2026-03-14T05:23:28.268Z [DEBUG] MCP server "vhiz": No token data found

This pattern repeats at ~1.2s intervals for the full session (11,735 total log lines, 6,485 of which are this single message).

Steps to Reproduce

1. Configure an MCP server with HTTP/SSE transport in .mcp.json
2. Start a Claude Code session
3. Use any tools (MCP or built-in) for a sustained period
4. Check the debug log: the "No token data found" line appears ~once per second from session start to finish

Is this a regression?

I don't know

Claude Code Version

2.1.76

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)