Composio Firewall is a runtime check for developers whose agents act through Composio, the layer that connects agents to 1,500+ apps and manages authentication and sandboxed execution. Co-founder Karan Vaidya announced it in October 2026 for teams that need limits applied while an agent is working. Tools are usually permitted when an integration is set up. Once the agent is running, it chooses the next call from emails, documents, and pages the developer has not reviewed, so an allowed action can still fall outside the task the user asked for. The company says Firewall evaluates each proposed action before it runs, using Jev, TypeSafe AI's decision model, and custom small language models tuned on Composio usage data. The check is meant to catch actions that are technically permitted but fall outside the user's task or the limits the developer and user set. On the return path, it reads tool results and blocks content carrying hidden instructions, such as a prompt injection in an email, a page, or a file, before that content enters the agent's context. Composio says Firewall is live for every developer on the platform, and that the check does not remove every risk.