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 36-40 of 76 articles in Engineering.

Engineering

MCP Spotlight: Resend MCP Server — The React-Email-Native Transactional Email Bridge, Full Audience Management, and the Communication Default for Agents

Jun 30, 2026Engineering

MCP Spotlight: Resend MCP Server — The React-Email-Native Transactional Email Bridge, Full Audience Management, and the Communication Default for Agents

The Resend MCP Server — the email-agent default of 2026. ~20 tools (emails, audiences, broadcasts, domains, webhooks, deliverability analytics), native React Email template support (JSX compiles at send-time), MIT-licensed. Built on the infrastructure Anthropic, Linear, and Vercel use.

Engineering

MCP Spotlight: Sequential Thinking MCP Server — Anthropic's Reference Implementation for Structured, Branchable, Revisable Reasoning

Jun 29, 2026Engineering

MCP Spotlight: Sequential Thinking MCP Server — Anthropic's Reference Implementation for Structured, Branchable, Revisable Reasoning

Anthropic's Sequential Thinking MCP Server — the reference implementation for structured agent reasoning. One tool (sequential_thinking), MIT-licensed, with three superpowers: revision (correct earlier thoughts), branching (explore alternatives in parallel), and expansion (adapt the scope mid-stream). The meta-tool pattern that improves every other tool the agent uses.

Engineering

MCP Spotlight: Anthropic Filesystem MCP Server — Sandboxed Read/Write, Allow-Listed Directories, and the Reference Architecture for File Access

Jun 28, 2026Engineering

MCP Spotlight: Anthropic Filesystem MCP Server — Sandboxed Read/Write, Allow-Listed Directories, and the Reference Architecture for File Access

The Anthropic Filesystem MCP Server is the reference implementation for safe file access in the MCP ecosystem — ~14 tools (read, write, edit, search, move, delete), MIT-licensed, with strict --allowed-directory sandbox + symlink resolution at the boundary. The architectural template every local-resource MCP server should copy.

Engineering

MCP Spotlight: Postgres MCP Pro — Configurable Read/Write Access, Schema-Aware Index Tuning & the Safety Pattern Every Database MCP Needs

Jun 27, 2026Engineering

MCP Spotlight: Postgres MCP Pro — Configurable Read/Write Access, Schema-Aware Index Tuning & the Safety Pattern Every Database MCP Needs

Postgres MCP Pro by Crystal DBA — configurable read/write access at the database role level, schema-aware index tuning, migration generation with safety checks, EXPLAIN plan visibility, MIT-licensed. The defense-in-depth pattern every database MCP server should copy.

Engineering

MCP Spotlight: Stripe MCP Server — 25 Tools, OAuth 2.0 + DCR, Knowledge Base Search, and the Payment-Agent Default of 2026

Jun 26, 2026Engineering

MCP Spotlight: Stripe MCP Server — 25 Tools, OAuth 2.0 + DCR, Knowledge Base Search, and the Payment-Agent Default of 2026

Stripe's official MCP Server — 25 tools organized into transactional layer (payments, subscriptions, invoices, refunds, disputes) + knowledge-base layer (Stripe docs search, support articles, changelog). v0.3.3 (April 2026) added OAuth 2.0 + DCR. Apache 2.0 SDK, distributed via the Stripe App Marketplace.