feat: Add mcp-skills-plugin for MCP to Claude Skills conversion

[bjornslib]

Summary

• Adds mcp-skills-plugin that converts MCP servers to Claude Skills with progressive disclosure pattern
• Reduces context usage by 90%+ compared to native MCP loading
• Includes session start hook for auto-loading MCP Skills Registry

Features

• mcp-to-skill-converter skill: Converts MCP servers (stdio, http, sse) to Claude Skills
• Session start hook: Automatically loads MCP Skills Registry on startup
• Python CLI: List, convert single, or batch convert all MCP servers
• Auto-updates: Updates index.json and removes converted servers from .mcp.json

Test plan

• Plugin validated: plugin.json, hooks.json are valid JSON
• Shell script validated: bash syntax check passed
• Python script validated: py_compile check passed
• YAML frontmatter validated: SKILL.md has valid YAML

Context Savings

Scenario	Native MCP	As Skill	Savings
Idle	30-50k tokens	~100 tokens	99%+
Active	30-50k tokens	~5k tokens	85%+
Executing	30-50k tokens	0 tokens	100%

Standalone Repository

Also available at: https://github.com/bjornslib/mcp-skills-plugin

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Author: Bjorn Schliebitz

🤖 Generated with Claude Code

[bjornslib]

Found your Github and thought why not submit this skill too :)

[daymade]

Thanks for the PR — this is a great idea and I’m excited to get it in. I’d like to merge once a few blocking usability issues are fixed (no security issues found, but these will currently break a fresh user flow):

• Docs reference a central executor (.claude/skills/mcp-skills/executor.py --skill ...), but the converter only generates per‑skill executors. Either add the central executor or update all docs/templates to use per‑skill paths.
• Registry template uses --skills, but the generated executor only supports --list/--describe/--call. Please add --skills or update the template.
• The savings calculation divides by tool_count * 500; if a server exposes 0 tools this will crash. Please guard against zero.
• Docs say HTTP/SSE are unsupported, but the code supports them. Please align wording.
• Registry template suggests running the converter from .claude/skills/mcp-to-skill-converter, but the plugin installs under ${PLUGIN_DIR}/skills/.... Please update that path.

Also a couple integration assumptions to confirm (might be optional depending on how Claude Code expects plugins to be packaged):

• Marketplace entry points to ./mcp-skills-plugin, but that directory doesn’t contain a SKILL.md. If the marketplace requires a root SKILL, please add one or point the marketplace entry to ./mcp-skills-plugin/skills/mcp-to-skill-converter.
• README lists .claude-plugin/plugin.json in the plugin structure, but the PR doesn’t add it. Please either include the file or update the README.
• SessionStart hook uses a relative path .claude/skills/mcp-skills/SKILL.md and doesn’t use the hook JSON to resolve project root; if hooks don’t run from repo root, the registry will never load (always falls back to the template). Please confirm the working directory or update the hook to resolve the project path.

Happy to approve right after these are addressed. If you want, I can also help with a follow‑up PR to fix any of the above quickly.

[daymade]

Hi @bjornslib 👋

Just checking in on this PR! It's been 5 days since my review feedback on Jan 10th.

First, I want to say this is really valuable work — converting MCP servers to Claude Skills with 90%+ context savings is exactly the kind of innovation this marketplace needs. I'm genuinely excited to get this merged.

I know the review had quite a few items to address (5 blocking issues + 3 integration assumptions). If you're busy or stuck on any of them, I'm happy to help in whatever way works best:

Option 1: I can create a follow-up PR 🛠️
I can checkout your branch, fix the issues, and push directly (if you've enabled "Allow edits by maintainers"). This would be fastest.

Option 2: We can pair on it 🤝
If you prefer to maintain ownership, I can guide you through the fixes or we can tackle them together.

Option 3: Take your time ⏰
If you just need more time, no worries at all! Just let me know you're still working on it and I'll wait patiently.

Looking forward to hearing from you! If I don't hear back in the next few days, I'll assume you're busy and will go ahead with Option 1 to keep momentum going (with full credit to you for the original work, of course).

Thanks again for this contribution! 🙏