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Agent Control Specification (ACS)

A tiernew this week

Microsoft's open-source SDK that lets you define portable, auditable policy files controlling exactly what your AI agents can and can't do — across any framework.

Open Agent Control Specification (ACS) →Compare with alternatives

Kai's verdict

ACS is the right idea at the right time — treating agent guardrails as a first-class, portable artifact rather than a pile of system-prompt hacks is exactly what enterprise AI needs; just don't bet a regulated production workload on it quite yet while it's still in preview. (Verdict pending Phi's full review.)

Strengths

  • Framework-agnostic: ships with adapters for LangChain, OpenAI Agents SDK, Anthropic SDK, AutoGen, CrewAI, Semantic Kernel, and MCP tools out of the box
  • Portable policy-as-a-file: governance rules bundle with the agent and travel across environments, no per-deploy rewrites
  • Multi-checkpoint enforcement: intercepts agent behavior before input, before tool calls, after tool results, and before final output
  • Separates concerns cleanly — devs own agent logic, security/compliance teams own policy files, no code entanglement
  • MIT-licensed with formal RFC 2119 specs and 992+ conformance tests backing the implementation

Weaknesses

  • Public Preview only — Microsoft's own repo warns current profiles shouldn't yet be treated as hard security boundaries
  • Adoption depends on the broader ecosystem embracing the standard; fragmentation risk if competitors ship competing specs
  • Still early: policy-per-framework adapter behavior varies, and retrofitting onto existing large agent surfaces is genuinely painful

Best for

Enterprise dev and platform teams building production AI agents who need auditable, portable guardrails without baking governance logic into application code.

Pricing

Free (MIT open-source)

Fully open-source; installable via pip and npm. No paid tiers.

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