Facio Blog

Practical notes on human-reviewed AI agents.

Payload-powered product notes, security writing, HITL patterns, and operational guidance from the Facio runtime: long sessions, Placet approvals, audit trails, memory, providers, channels, tools, and Docker-first operations.

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Showing 21-25 of 76 articles in Engineering.

Engineering

MCP Spotlight: Sequential-Thinking MCP Server — Anthropic's Reference Implementation for Step-by-Step Reasoning Chains, Branching Thought, and Audit-Ready Thought Trajectories

Jul 15, 2026Engineering

MCP Spotlight: Sequential-Thinking MCP Server — Anthropic's Reference Implementation for Step-by-Step Reasoning Chains, Branching Thought, and Audit-Ready Thought Trajectories

The official Sequential-Thinking MCP Server by Anthropic — 1 tool (sequential_thinking), 1 primitive: structured thought trajectories with branching, revision, expansion, and synthesis. The structured-reasoning default that produces audit-ready reasoning paths. MIT-licensed, available via NPX or Docker.

Engineering

MCP Spotlight: Filesystem MCP Server — Anthropic's Reference Implementation for Sandboxed, Allowed-Directory-Scoped File Access

Jul 14, 2026Engineering

MCP Spotlight: Filesystem MCP Server — Anthropic's Reference Implementation for Sandboxed, Allowed-Directory-Scoped File Access

The official Filesystem MCP Server by Anthropic — ~14 focused tools covering read, write, edit, search, directory, metadata. Explicit allowed-directories allow-list at startup (deny-by-default), Roots-aware dynamic updates, image support. MIT-licensed, available via NPX or Docker. The local-file-access default for AI agents in 2026.

Engineering

MCP Spotlight: Stripe MCP Server — The Payments Bridge With Restricted API Keys, Customer-Portal Scope Isolation, and the Money-Movement Default for Agents

Jul 13, 2026Engineering

MCP Spotlight: Stripe MCP Server — The Payments Bridge With Restricted API Keys, Customer-Portal Scope Isolation, and the Money-Movement Default for Agents

The official Stripe MCP Server by Stripe — ~30 focused tools covering customers, payment intents, subscriptions, products, invoices, refunds, disputes, payouts. Restricted API Key support for per-resource + per-action scope isolation. PCI-scope minimization, webhook-first event model. The payment-automation default for AI agents in 2026.

Engineering

MCP Spotlight: Brave Search MCP Server — The Web-Wide Search Bridge With Independent Index, Local-First Privacy Options, and the Research-Default Reference

Jul 12, 2026Engineering

MCP Spotlight: Brave Search MCP Server — The Web-Wide Search Bridge With Independent Index, Local-First Privacy Options, and the Research-Default Reference

The official Brave Search MCP Server by Brave Software — ~8 focused tools covering web, local, image, video, and news search. Brave's independent web crawler (no Google/Bing dependency), privacy-first (no user tracking), 2000 queries/month free tier, EU presence. The independent-index search default for AI agents in 2026.

Engineering

MCP Security Architecture 2026: Threat Models, Sandboxing, and the Defense-in-Depth Layers Every Production Agent Deployment Needs

Jul 11, 2026Engineering

MCP Security Architecture 2026: Threat Models, Sandboxing, and the Defense-in-Depth Layers Every Production Agent Deployment Needs

The defense-in-depth reference architecture every team deploying MCP in production needs. Six layers: server verification → process sandboxing → credential isolation → per-tool RBAC → HITL approval → audit trail. Plus prompt-injection defense and multi-agent trust boundaries. Companion to the MCP Spotlight series.