TL;DR: Enterprise agent harnesses fail when they treat the agent loop, tool calls, and untrusted execution as one trust domain, according to Stacklok’s analysis of Mecatl and competing harness categories. The real governance issue is that policy, identity, and audit controls must sit at the harness boundary, because agentic systems can otherwise bypass the very controls they are supposed to obey.
Editorial analysis by NHI Mgmt Group, based on content published by Stacklok: “What’s the Best Agent Harness for Enterprise AI Infrastructure? (2026)”.
Key questions
Q: What breaks when an AI agent harness runs tool calls and execution in the same trust domain?
A: Policy becomes advisory, identity checks lose their enforcement point, and audit logs can no longer distinguish intended tool use from unsafe execution.
Q: Why do delegated identities matter for enterprise AI agents?
A: Delegated identities let teams tie agent activity to a real principal, scope what the agent can do, and revoke access cleanly when needed.
Q: How do teams know whether an agent harness is actually enforcing governance?
A: A harness is enforcing governance when policy decisions, identity verification, and audit logging happen at runtime boundaries rather than inside the agent itself.
Practitioner guidance
- Define the harness boundary as a control boundary Map where policy enforcement, identity checks, and audit hooks attach in the agent runtime, then reject designs where those controls only exist inside the agent logic.
- Separate agent execution from untrusted tool calls Require distinct runtime contexts for the loop, external tools, and code execution so that a compromise in one layer does not inherit the others’ privileges.
- Assign delegated identities to agents Issue each agent a verifiable identity that maps to a human owner and a bounded permission scope, then revoke that identity independently of the host process.
Bottom line: Enterprise agent harnesses are only governable when the runtime boundary separates the agent loop, tool use, and untrusted execution.
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Harness separation is now an identity control, not an architecture preference. Enterprise agent systems collapse when the agent loop, tools, and execution share one trust domain because governance stops having a place to attach. That makes the harness boundary the real control plane for policy, identity, and audit, which is the point at which enterprise AI moves from experimentation to governed production.
A few things that frame the scale:
- AI-related credential leaks surged 81.5% year-over-year in 2025, with the surrounding AI infrastructure leaking 5x faster than core LLM providers, according to the State of Secrets Sprawl 2026.
- Enterprise AI use rose from 55% of organisations in 2023 to 88% in 2025, according to McKinsey’s Global Surveys on the State of AI.
A question worth separating out:
Q: What is the difference between an agent framework and an agent harness?
A: An agent framework gives humans abstractions to assemble an agent. An agent harness starts with a working agent that already has iteration, tools, context handling, and safety controls wired together. Frameworks help you build. Harnesses let the model operate, extend its skills, and complete tasks inside a ready-made control structure.
👉 Read our full editorial: Enterprise agent harness governance: why separation and identity matter