# NousResearch/hermes-agent · MCP stdio server failure isolation and reconnect resilience

## Open now

- Nothing open on GitHub.

These issues and fixes address how a single failing stdio MCP server can destabilize the entire MCP bridge, causing healthy servers' tools to become unavailable. The work covers isolating failing servers, adding per-server circuit breakers, and improving reconnection logic to re-register tools when a server recovers.

## TL;DR

- 4 member(s): 0 open issue(s), 1 closed issue(s), 0 open PR(s), 1 merged PR(s), 2 PR(s) closed without merging.
- A fix was merged to main in PR #68660. Verify it addresses your case.
- **Recommended:** read PR #68660 (and any competing PRs below) before filing. Confirm the merged change covers your symptom.

## Maintainer resolution verdict

- Internal-tracker verdict over this cluster's issue members: `unresolved`. This is distinct from the fix status above. Weigh it yourself.

## How this cluster was grouped

- Link evidence (`STRUCTURAL_SPANNING`): every member is connected by structural evidence: shared changed files, or a closing/superseded reference.
- Pairwise link density `0.50`: the share of member pairs that carry a link, counting a structural link in full and a relevance-only link at 0.36. `1.00` means every pair is linked.

## Closed / duplicate issues

- #50394: A single failing stdio MCP server churns the whole MCP bridge — healthy servers' tools become "Unknown tool" at runtime

## Prior & competing PRs

- **#68660: fix(mcp): stdio discovery cooldown, message-less transport classification, zero-connected retry latch**. merged to main · fix tier `verified`
  - maintainer direction: category `merged`
  - files: `contributors/emails/[redacted:email]`, `contributors/emails/[redacted:email]`, `hermes_cli/mcp_startup.py`, `tests/hermes_cli/test_mcp_startup.py`, `tests/test_tui_entry_mcp_owner.py`, `tests/tools/test_mcp_bridge_single_failure.py`, `tests/tools/test_mcp_resource_content.py`, `tests/tools/test_mcp_tool.py`, `tests/tools/test_mcp_tool_session_expired.py`, `tools/mcp_tool.py`, `tui_gateway/entry.py`
- **#50482: fix(mcp): per-server connection circuit breaker to stop the restart storm (#50394)**. closed without merge
  - maintainer direction: category `uncategorized`; implication `needs_llm`; refs `472c0681594ccd137666fc2b87f4913d2e6cc5b0`
- **#50589: fix(mcp): isolate a single failing stdio server from the bridge**. closed without merge
  - maintainer direction: category `merged_via`; implication `superseded`; refs `#68660`

## Fix status

- Merged to main in PR #68660 (cited above). No release data is tracked. Verify downstream.
- Fix last verified (merged) `2026-07-21`.
- Subsystem: `mcp`