MCP server connection lost after context compaction — tools unavailable until new session

[ramsyman]

Description

After context compaction occurs, MCP server tools become completely unavailable for the rest of the session. The only workaround is to start a new session.

This was also reported in NeuralNomadsAI/CodeNomad#344, where the CodeNomad maintainer confirmed this is an OpenCode-level issue.

Steps to Reproduce

1. Start a session with MCP servers configured
2. Use MCP tools extensively (large tool outputs, many calls)
3. Wait for or trigger context compaction (~95% context window)
4. Attempt to call any MCP tool after compaction

Expected Behavior

MCP server connections are re-established after compaction. Tools remain available throughout the session.

Actual Behavior

All MCP tool calls fail after compaction. The tools are simply gone — no error, no reconnect attempt. A full new session is required to restore MCP functionality.

Impact

Any workflow relying on MCP tools (e.g. database tools, agent registries, custom servers) is silently broken after compaction. This is especially problematic for long-running sessions where compaction is expected.

Environment

• OpenCode TUI (darwin)
• MCP servers configured via config
• Model: claude-sonnet-4-6

Related

• [Bug]: MCP tools unavailable to agent after context compaction NeuralNomadsAI/CodeNomad#344

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• Bug: MCP tools permanently lost mid-session after single transient listTools() failure — no retry, no reconnect #17099: MCP tools permanently lost mid-session after a transient listTools() failure — same symptom (tools gone, restart required), possibly the same root cause where context compaction triggers a listTools() error path that permanently evicts the MCP client
• [FEATURE]: Re-announce tools after context compaction #20290: Feature request to re-announce tools after context compaction — directly addresses tool unavailability after compaction from the model-awareness side

It may be worth reviewing those issues to see if they overlap with what you're experiencing.