feat(skill): enable advanced MCP tool use with mcpx

[cs50victor]

Summary

Adds mcpx as a builtin skill providing lightweight MCP tool access via CLI.

What mcpx provides:

• On-demand tool discovery without loading all schemas upfront (zero token cost)
• Daemon mode for stateful operations (browser automation, database transactions)
• Simple CLI interface: mcpx server/tool '{"args": ...}'

Pain points addressed:

Issue	Problem	How mcpx helps
#882	MCP startup takes 2-3 minutes	Daemon mode provides instant tool availability
#878	Tools show connected but not exposed	Reliable discovery via mcpx / mcpx grep
#949	No way to prefer custom tools	mcpx grep "*pattern*" enables tool selection

Changes

• Added mcpxSkill to src/features/builtin-skills/skills.ts
• Skill includes:
  • Quick reference for common commands
  • Daemon mode documentation for stateful operations
  • Decision tree for when to use daemon vs direct calls
  • Anti-patterns section

Test plan

• bun run typecheck passes
• Manual testing: invoke skill via /skill mcpx in OpenCode

Note

mcpx is available at: https://github.com/cs50victor/mcpx

Install: brew install cs50victor/tap/mcpx or bun install -g mcpx

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Summary by cubic

Adds mcpx as a builtin skill to discover and invoke MCP tools via a simple CLI, with a daemon mode for stateful workflows. Improves tool availability and selection, addressing #882 (startup delay), #878 (tools not exposed), and #949 (tool preference).

• New Features
  • Added mcpxSkill to builtin skills for on-demand MCP tool discovery without schema preload (zero token cost).
  • Supports daemon mode for persistent state (browser automation, database transactions).
  • Includes quick command reference, decision tree, and anti-patterns in the skill template.
  • Enables reliable tool search and selection via grep.

^{Written for commit 58a659c. Summary will update on new commits.}

[github-actions]

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[cs50victor]

I have read the CLA Document and I hereby sign the CLA

[cubic-dev-ai]

No issues found across 1 file

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

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