--- title: "Agent, skill, or MCP? Which to use and when to use them | AWS’ Clare Liguori" url: https://daily.dev/posts/agent-skill-or-mcp-which-to-use-and-when-to-use-them-aws-clare-liguori-o5ujnopp0 source_url: https://devinterrupted.substack.com/p/agent-skill-or-mcp-which-to-use-and type: article source: "Dev Interrupted" published: 2026-08-18T16:45:33.354Z updated: 2026-08-18T17:24:09.274Z tags: ["open-source", "ai-agents", "mcp", "claude-code", "context-engineering"] reading_time: 5 upvotes: 0 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Agent, skill, or MCP? Which to use and when to use them | AWS’ Clare Liguori **[Dev Interrupted](https://daily.dev/sources/devinterrupted)** · 5 min read · 0 upvotes · 0 comments ## Summary A newsletter roundup covering agentic AI architecture debates, including how teams should choose between building custom agents, skills, or MCP servers, featuring AWS engineer Clare Liguori's take on the simplified MCP spec. Also covered: Tim O'Reilly's warning against proprietary AI lock-in, Anthropic making auto mode default in Claude Code, Meta's Muse Glimmer open local agentic model, the importance of SDLC context engineering, Uber's 'rearward deployed engineers' strategy, and a study finding generalized coding agent skills outperform personalized ones. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Is auto mode now the default permission setting in Claude Code? Yes, Anthropic made auto mode the default permission setting for Claude Code on Pro, Max, and Team plans, whereas it was previously an experimental opt-in feature. The system routes every tool call through a classifier that blocks irreversible or destructive actions on the local machine. Anthropic cited that users were manually approving 97% of prompts anyway, often without real scrutiny. _Track how Claude Code's evolving permission model affects your workflow by following coding agent updates on daily.dev._ ### What is Meta's Muse Glimmer model and how much memory does it need to run locally? Muse Glimmer is a 30 billion parameter open-weight agentic model from Meta released under an Apache 2.0 license, requiring only 20 GB of memory to run on consumer-grade local hardware without cloud dependencies. It was distilled from a larger teacher model and performs well on benchmarks measuring long-form document synthesis. _Developers evaluating local versus cloud agent options can follow open model releases like this on daily.dev._ ### Do personalized custom skills actually improve coding agent productivity compared to generalized skills? No, an empirical study of developer interaction histories across hundreds of real-world sessions found that gains from highly personalized, customized skills were only marginal. Generalized skills pooled and distributed across many developers produced the largest and most consistent productivity improvements, suggesting teams should consolidate and share what works rather than over-customize individually. _Teams deciding how to standardize agent skills across engineers can track findings like this on daily.dev._ ## Similar posts on daily.dev - [MCP servers vs. skills: Choosing the right context for your AI](https://daily.dev/posts/mcp-servers-vs-skills-choosing-the-right-context-for-your-ai-zvdsezrz1) · Red Hat Developer · 1 upvotes · 0 comments - [EP202: MCP vs RAG vs AI Agents](https://daily.dev/posts/ep202-mcp-vs-rag-vs-ai-agents-jowyr3vcd) · ByteByteGo · 5 upvotes · 0 comments --- Tags: [#open-source](https://daily.dev/tags/open-source), [#ai-agents](https://daily.dev/tags/ai-agents), [#mcp](https://daily.dev/tags/mcp), [#claude-code](https://daily.dev/tags/claude-code), [#context-engineering](https://daily.dev/tags/context-engineering) [View this post on daily.dev](https://daily.dev/posts/agent-skill-or-mcp-which-to-use-and-when-to-use-them-aws-clare-liguori-o5ujnopp0)