Developer builds automated red-team tool after finding prompt injection flaw in own AI agent

A developer discovered a critical security gap while building an AI agent capable of calling external tools, finding that a prompt injection attack disguised as a fake tool error message could sometimes leak records. Prompt injection has ranked as OWASP's top vulnerability for LLM applications since the organization's first such list, yet the developer noted a wide gap between theoretical awareness and actual resistance testing. Manual red-teaming proved informative but unreliable, as test cases were skipped and no records were kept, making it impossible to verify whether fixes held. To address this, the developer created AgentRedTeam, a tool that takes an agent's description and tool list, then runs adversarial simulations covering prompt injection, tool abuse, and data exfiltration, producing a prioritized, rule-based hardening report. The developer cautions that the tool is meant as a structured first pass to complement human testing, not as a security certificate or substitute for dedicated manual review.