Nexus Agent is an AI support infrastructure platform that allows businesses to create, configure, test, and deploy AI support agents using their existing knowledge and backend tools. The platform ingests websites, PDFs, TXT, Markdown, and FAQ content, cleans and chunks the data, generates embeddings using Sentence Transformers, and stores tenant-isolated vectors in Qdrant for semantic retrieval. Every response passes through a deterministic 6-point safety and grounding gate covering intent confidence, vector similarity, forbidden claims, lexical grounding, high-risk phrases, and empty knowledge bases. Unsupported or risky queries are safely rejected or escalated to human support. Nexus Agent also provides an MCP-based tool ecosystem for actions such as knowledge search, FAQ lookup, company policy lookup, support ticket creation, human escalation, order tracking, business-hours lookup, and shipping calculations. Tool execution is protected through tenant authorization, per-agent permissions, schema validation, and audit logging. The platform includes a React + Vite admin console, interactive agent playground, knowledge ingestion interface, MCP tool manager, conversation audit, analytics, and a universal vanilla JavaScript widget that can be embedded into any website using a single script tag. The system is designed as a multi-tenant AI agent infrastructure layer with server-side secrets, prompt-injection protection, PII redaction, rate limiting, isolated vector retrieval, and complete tool execution auditing.