Feature Request: CLI Commands for MCP Server Enable/Disable (Hook Automation Support)

[learnwithcc]

Feature Request: CLI Commands for MCP Server Enable/Disable (Hook Automation Support)

Problem Statement

Claude Code v2.0.10 introduced the ability to enable/disable MCP servers within a session via the @ UI menu. This is excellent for manual control, but there's currently no way to programmatically toggle MCP servers via CLI commands. This prevents automation through hooks and scripts.

Current Limitations:

1. The claude mcp CLI only supports add, remove, list, and get - no enable/disable/toggle
2. MCP servers consume context window even when not actively needed
3. No way to automate MCP lifecycle based on project context, skills, or workflows
4. The @ menu toggle is UI-only with no programmatic equivalent

Use Case: Skill-Based MCP Management

I have several Claude Code skills that require specific MCP servers, but only occasionally:

Example Skills:

• accessibility-compliance-expert skill → Needs Playwright MCP for visual testing
• library-documentation research → Needs Context7 MCP for API docs
• database-analysis tasks → Needs database MCP tools

Current Problem:

• All MCP servers load at session start, consuming 15-20% of context window
• Playwright MCP alone: ~8-10k tokens, but only needed for visual testing tasks
• Context7 MCP: ~5k tokens, but only needed for documentation lookup
• These servers sit idle 90% of the time, wasting valuable context

Desired Workflow:

# SessionStart hook - enable only baseline MCPs
claude mcp disable playwright
claude mcp disable context7

# PreToolUse hook - enable when specific skill triggers
if [[ "$context" =~ "accessibility-compliance-expert" ]]; then
  claude mcp enable playwright
fi

# Stop hook - disable when skill completes to free context
claude mcp disable playwright

Proposed CLI Commands

Add these commands to the claude mcp CLI:

# Enable an MCP server in current session (doesn't modify config files)
claude mcp enable <server-name>

# Disable an MCP server in current session (doesn't modify config files)  
claude mcp disable <server-name>

# Toggle an MCP server's state
claude mcp toggle <server-name>

# Show current enabled/disabled state of all servers
claude mcp status

Example Usage:

$ claude mcp status
✓ pieces-mcp          enabled   (3.2k tokens)
✗ playwright          disabled  
✓ sequential-thinking enabled   (1.8k tokens)
✗ context7            disabled
✓ stripe              enabled   (4.1k tokens)

Total active: 3/5 servers (9.1k tokens)

$ claude mcp disable stripe
✓ Disabled stripe (freed 4.1k tokens)

$ claude mcp enable playwright  
✓ Enabled playwright (loaded 8.3k tokens)

Hook Integration Example

SessionStart Hook (.claude/hooks/session-start.sh):

#!/bin/bash
# Disable rarely-used MCPs at session start

claude mcp disable playwright
claude mcp disable context7

# Enable based on project type
if [[ -f "package.json" ]] && grep -q "@playwright/test" package.json; then
  claude mcp enable playwright
  echo "📊 Enabled Playwright MCP for testing project"
fi

PreToolUse Hook (.claude/hooks/pre-tool-use.sh):

#!/bin/bash
# Enable MCP when specific skill triggers

# Read context from environment
context="$CLAUDE_CONTEXT"

if [[ "$context" =~ "accessibility-compliance-expert" ]]; then
  # Enable Playwright only when accessibility skill is active
  claude mcp enable playwright
fi

SubagentStop Hook (.claude/hooks/subagent-stop.sh):

#!/bin/bash
# Free up context when specialized subagent completes

subagent_name="$CLAUDE_SUBAGENT_NAME"

if [[ "$subagent_name" == "accessibility-compliance-expert" ]]; then
  claude mcp disable playwright
  echo "♻️ Freed context: disabled Playwright MCP"
fi

Benefits

1. Context Window Optimization

   • Load MCP servers on-demand instead of all-at-once
   • Free context by disabling servers when done
   • Optimize for long development sessions with varying needs

2. Skill-Based Automation

   • Skills can automatically enable their required MCPs
   • Clean up after themselves to avoid context bloat
   • Smooth integration with subagent workflows

3. Project-Based Profiles

   • SessionStart hooks enable relevant MCPs based on project type
   • Testing projects get Playwright, database projects get DB tools
   • No manual toggling required

4. Hook Ecosystem Integration

   • PreToolUse, Stop, SubagentStop hooks manage MCP lifecycle
   • Automated workflows without manual intervention
   • ADHD-friendly: reduces decision fatigue

Implementation Considerations

Session-Level Only:

• These commands affect current session only (not config files)
• Changes don't persist across session restarts
• Config files (.mcp.json, settings.json) remain unchanged

Relationship to @ Menu:

• CLI commands should mirror the behavior of the UI @ toggle
• Both methods (UI and CLI) modify the same session state
• claude mcp status should reflect current state regardless of how it was set

Security:

• Respect existing approval workflows for project-scoped servers
• Honor managed-mcp.json enterprise policies
• Enabling a disabled server may still prompt for project approval if not yet granted

Error Handling:

$ claude mcp enable nonexistent-server
❌ Error: MCP server 'nonexistent-server' not found in configuration
   Available servers: pieces-mcp, playwright, sequential-thinking

$ claude mcp disable playwright
✓ Disabled playwright

$ claude mcp disable playwright  
⚠️ Warning: playwright is already disabled

Why This is Different from Existing Issues

While several issues request runtime toggling (#6309, #6638), this request specifically focuses on:

1. CLI automation (not just UI toggle, which already exists)
2. Hook integration (SessionStart, PreToolUse, Stop, SubagentStop)
3. Skill-based workflows (automated MCP lifecycle management)
4. Concrete implementation (specific command syntax and examples)

Alternative Solutions Considered

1. Project-scoped .mcp.json with enabledMcpjsonServers

   • Problem: Only works at session start, not mid-session
   • Problem: Requires session restart to change

2. PreToolUse hooks blocking MCP tools

   • Problem: Doesn't free context, server still loaded
   • Problem: Shows confusing errors instead of smooth workflow

3. Multiple Claude Code profiles/sessions

   • Problem: Fragments workflow across sessions
   • Problem: Loses conversation context when switching

Related Issues

• Feature Request: Runtime MCP Server Toggle #6309 - Runtime MCP Server Toggle (general request)
• Add dynamic loading/unloading of MCP servers during active sessions #6638 - Dynamic loading/unloading (context optimization focus)
• [FEATURE] MCP Tool Filtering: Allow Selective Enable/Disable of Individual Tools from Servers #7328 - Tool-level filtering (related but different scope)
• Having multiple MCP servers running Eats into Context Window #3036 - MCP servers eating context window

Priority

High - This enables a powerful automation workflow that significantly improves context management and integrates with Claude Code's existing hook system.

---

Environment:

• Claude Code Version: 2.0.22 (latest)
• MCP Servers: 5-7 servers configured per project
• Context Impact: 15-20k tokens consumed by idle MCP servers

[github-actions]

Found 3 possible duplicate issues:

1. Feature Request: Runtime MCP Server Toggle #6309
2. Add dynamic loading/unloading of MCP servers during active sessions #6638
3. Feature Request: Improve Claude Code Token Management with MCP Servers #7172

This issue will be automatically closed as a duplicate in 3 days.

• If your issue is a duplicate, please close it and 👍 the existing issue instead
• To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

[mtrefilek]

@claude

Found 3 possible duplicate issues:
#6309

I don't think this fully encapsulates this issue which would allow for running in hooks

[dlecan]

That's exactly what I'm looking for

[ppf]

It's exactly what I need. It could be the massive update for context management.
Anthropic introduced some great tools in the API SDK recently:

• Tool Search Tool, which allows Claude to use search tools to access thousands of tools without consuming its context window
• Programmatic Tool Calling, which allows Claude to invoke tools in a code execution environment reducing the impact on the model’s context window
• Tool Use Examples, which provides a universal standard for demonstrating how to effectively use a given tool

https://www.anthropic.com/engineering/advanced-tool-use
CC should use these features.

[github-actions]

This issue has been inactive for 30 days. If the issue is still occurring, please comment to let us know. Otherwise, this issue will be automatically closed in 30 days for housekeeping purposes.

[yakimoto]

Looking for this as well -- this would enable context auto load / offload dependent on hooks