Day 12: MCP Ultra-Hard Mode — Editing the Config Safely, Building Your Own MCP Server in n8n, Opal, Cross-LLM Memory, and an Early Look at Claude Cowork

claude_desktop_config.json is a list of installed servers, each with a name and a run command in a syntax 'Node.js can understand' (npx). Reached via Settings > Developer > Edit Config. It is the gateway to mcp.so's 17,433 servers and to any server you build. The safety rule for non-developers: paste the current config and the new server's snippet into Perplexity/ChatGPT/Claude/Gemini, ask it to merge, paste the result back, save, restart Claude, test. Vetting: 'visit server' -> GitHub stars and forks - Firecrawl's 5,300 stars / 588 forks is trusted; 5-10 is a risk; some servers also need API keys from the tool's own site. Demo installed MCP Advisor, a server that recommends other servers.

Requirement: public API documentation. Steps: open the docs (Gamma's developer page - use its 'Ask AI' / 'copy markdown' / Claude shortcut), ask Claude for the request in cURL for the task ('generate a PPT with input text, preserve text mode'). In n8n: new workflow, MCP Server Trigger node as entry point; add an HTTP Request node as a tool and Import cURL (headers and params fill in); for anything the AI should decide at runtime choose 'let the model define'; rename the tool descriptively ('Create PPT'); Publish; copy the production URL; paste it into the server command line of the Claude config (replacing the placeholder); restart Claude Desktop - the tool appears in the connector list. Live: Claude drafted a 'WEF Davos 2026 AI discussions' outline and called the new tool; the deck appeared in Gamma. Generalizes to CRMs and anything else with docs (a 'Hagen'/HighLevel-type CRM is named). The workbook repeats the recipe with a free Gmail server; breakout fixes: disable VPN, re-auth Gmail, reboot Claude Desktop.

Google Labs' Opal turns a plain-English description into a visual multi-step AI workflow (inputs -> prompt template -> research/extraction -> scoring -> output). Geo-restricted: Urban VPN, NordVPN or similar set to US/Europe/UK/India. Best practice: draft an elaborate prompt in ChatGPT/Claude/Gemini with web search on, then paste into 'create new.' Demo 1: Stock Analyzer - symbol, exchange, horizon, risk tolerance, currency, sector benchmark -> fundamental-health, valuation and profitability scores -> buy/hold/sell with citations. Demo 2: a Trigonometry Tutor for a 7-10 year old with a Nano Banana Pro image and an auto-generated concept video. Limit stated plainly: 'it is not something that you can build for clients' - not deployable outside Opal, 'n equal to 1' POC tooling; Claude can replicate the same logic as a shareable artifact.

Framing: vendor memory creates switching costs (the aisle-seat example - an agent booking flights should know your preference wherever it runs). Fix: a third-party memory layer connected to each LLM via MCP; named for their security guarantees - Super Memory and mem0. Demo: sign in with Google, generate an API key, add the Super Memory MCP server to the Claude config, tell Claude to store facts (name, INFJ, favourite food vegetable biryani, anime tastes incl. Death Note). New chat, no context: 'recommend anime' -> Monster and Psycho-Pass, reasoned from the stored preference. Boundaries: small discrete facts, not bulk documents - 'RAG is a database... I'm talking about usable, reusable memory... a very personal database.' Pieces goes further: an OS-level layer recording every action and coding session locally, 'your own private Internet', 16 GB RAM minimum - it crashed his machine, so no demo.

Cowork: a tab beside chat in Claude Desktop, Mac-only research preview on the Max plan at recording, 'almost just like a week back.' It connects to local folders, shows step-by-step progress, and lets you start a second task while the first runs. Demo 1: a cluttered Downloads folder - Cowork asked clarifying questions (organize by type? delete DMG installers? dedupe?), got 'delete installers, don't dedupe, just organize', built folders, moved files; verified in Finder. Demo 2: summarized a Lenny's Podcast transcript (Dan Shipper) into structured points. If the tab is missing, the rollout has not reached you. Claude Code: he saw a tweet about Remotion, gave Claude Code the tutorial URL, and got a working programmatic video with zero coding - taught as an 'experimental mindset', with the caveat 'Claude Code is the last thing you should try' until fundamentals are solid.

Local: for confidential legal review (300 pages, no internet) run open models via Ollama on a dedicated box - even a Mac mini M4; Ollama serves a local URL you paste into the n8n node, no key ('Jupiter OSS' = gpt-oss, 120B option); models can live on an external disk. RAG inputs: .md, .txt, .json beat PDFs (OCR). Website chatbot from n8n: Webhook trigger + Respond to Webhook, shown with a Lovable front end. Scheduling: make a workflow run on a randomized, non-spammy cadence by pasting its JSON into Claude and asking for a Schedule trigger plus a random-delay node, then re-import. n8n 'evaluations' = QA tests for expressions and edge cases before production. Voice: Vapi for complex voice-only agents, Retell for simpler voice + chat. Video from epics for kids: Claude script -> Sora 2 / Veo 3 / Kling via fal.ai. Cold-email logos: 16x16, JPG, kilobytes. LinkedIn: HeyReach, Relevance AI. Gmail MCP 'lazy' with Sonnet 4.5 - nudge with dates and subjects. Multiple RSS feeds: a configuration node listing URLs so the reader runs per feed. Free templates: harshad.com/n8n (as heard). Client acquisition: network, portfolio content, cold outreach, ads.