Shaping what Azure SRE Agent does: Tool Permissions and Hooks

Microsoft

Jun 02, 2026

When an AI agent runs against production, the first question every security team asks is "What can it do, who decided it could, and what stops it from doing something it should not."

Azure SRE Agent reached general availability in March. Since then, teams inside Microsoft and customers running it against real production workloads have asked for the same thing: finer-grained controls over what the agent can do on its own and a clear answer to who governs each call that reaches a tool.

Today at Build 2026, we are releasing global tool access policies as one of a set of new governance controls. This post covers how they work. Tool access policies give security and platform teams a single place to define which tools the agent can invoke, under what conditions, and what requires human approval before it runs. Underneath those policies sits the identity the agent runs as the bedrock that every other control layer depends on. It is defense in depth applied to agent behavior: layers of control, each one holding on its own, so that governing the agent is something you can read, audit, and reason about as you scale it across production.

Identity is the bedrock: managed identity today, agent identity next

Start here, because nothing else matters if you skip it. The identity the SRE Agent runs as, and the Azure RBAC role assignments on that identity, are the most powerful boundary the agent works inside of. If your role assignments do not grant the agent access to a resource, none of the controls below come into play, because the agent cannot reach the resource to begin with. Network rules, tool permissions, hooks, and connector contracts all sit on top of an RBAC story that you write. The features in this post add layers above that floor. They do not replace it.

Today the SRE Agent operates as a managed identity, and your RBAC role assignments on that identity govern what it can do. This is the bedrock, and it is the same model your other Azure workloads already use. You assign roles, you scope them, and the agent inherits exactly what you granted and nothing more.

Everything that follows assumes the bedrock is in place. With identity settled, the next question is the obvious one: where is the agent allowed to send its traffic?

Permissions: govern what the agent does with a tool

Identity decides what the agent can reach. Permissions decide what the agent does with the access it has, down to the individual tool. Two levels cover the range: a point-and-click grid for the common cases, and hooks when a decision needs your own code.

The grid is the easy mode. Every tool the agent can use, built-in tools along with MCP servers, services, and custom tools, shows up in one searchable list with two switches. On/Off sets whether the tool is available at all; turn it off and the agent cannot use it. Allow/Ask sets what happens when it is on: Allow lets the agent run the tool automatically, Ask requires a human to approve every time, except in Autonomous mode. Select tools in bulk to flip a whole category at once, filter by category or permission, and use the Advanced permissions tab when you want rules that apply at global, per-agent, or per-thread scope instead of tool by tool. Defaults stay put until you touch them, and the engine is fail-closed: if a rule cannot be evaluated, the call is blocked rather than allowed. That covers most of what teams need.

Underneath those switches are three rules, allow, ask, and deny, and the Advanced tab is where you set them by scope. Global rules apply to every agent and thread, Agent rules to one custom agent, Thread rules to a single conversation. Deny is the hard one: it blocks the tool outright no matter the run mode, and a deny at a higher scope always wins, so an Allow at thread scope cannot reopen something denied globally. That split is deliberate. A platform team sets the Global guardrails that should never be crossed and the Asks that always need a human, and service teams add their own Allow rules at Agent scope for routine work, without being able to override the guardrails above them.

Platform team, Global scope:

deny: bash(az * delete *) - never delete, on any agent or thread
deny: bash(kubectl delete *)
ask: bash(az webapp restart *) - always confirm, even in Autonomous
allow: bash(az monitor *) - auto-approve monitoring queries

Service team, Agent scope:

allow: bash(kubectl get *) - routine read-only work
allow: bash(kubectl describe *)

Two details make this safe to lean on. Rules match the canonicalized tool invocation rather than the raw text, so enforcement holds no matter how the command was assembled. And fail-closed has a softer edge than a hard stop: a cached last-known-good policy covers transient failures, so a blip in the policy store blocks the call rather than silently widening access.

You can find these under Capabilities > Tools

Tools permissions.Advanced Tool permissions.

The layer worth spending time on is hooks. Allow and Ask answer "should this tool run." Hooks answer "should this specific call run, given exactly what it is about to do." A hook fires before the agent runs a tool and receives the actual call, parameters and all. Your code then decides the outcome and can reshape it: rewrite parameters before they are sent, inject extra context into the pipeline as a user message so the agent reconsiders before its next step, block the call outright, or redirect the agent toward a safer path. Because your code sees the real parameters, the decision can depend on anything you can express in code: which resource the call targets, whether a value falls outside an allowed range, the time of day, the result of an external policy lookup. This is where you write the rule the grid cannot.

Two kinds of hook, mixable on the same agent. Command hooks are a script you write; reach for these when code is enough. Prompt hooks put a separate LLM in the loop as a judge that evaluates the call in context; reach for these when the decision needs reasoning rather than a fixed rule. A real example from our own internal test agent: when the agent tries to list files through the shell with ls or dir, a hook blocks the call. The agent absorbs the signal, reconsiders, and reaches for the ListDir tool instead. The hook did not argue with a human. It shaped what happened next. As with the grid, configure nothing and the agent behaves exactly as it does today. Both are additive.

Authoring one is a short form. You name the hook, pick the event (Pre Tool Use, so it runs before the call), and set a tool matcher, either picked from the tool menu or written as a regex like (FetchWebpage|SearchMemory) with anchors and lookaheads when you need them, so the hook fires only on the calls you care about. You set a timeout and a fail mode (Block, so a hook that errors or hangs stops the call rather than waving it through), and you write the body in Bash or Python. A command hook reads the call as JSON on stdin, the event name, the tool name, its parameters, and the call id, and answers on stdout. Print nothing and exit zero to allow. Return a block decision with a reason to stop the call, and that reason is what the agent reads back. You can also substitute: run a cheaper or safer version yourself, block the real call, and hand your own output back as the result, so the agent never runs the expensive or risky original.

#!/bin/bash
input=$(cat)
tool=$(echo "$input" | jq -r '.tool_name')

# Block one tool, with a reason the agent will read
if [ "$tool" = "ExampleToolName" ]; then
  echo '{"decision":"block","reason":"Blocked ExampleToolName by hook policy."}'
  exit 0
fi

# Otherwise allow: print nothing and exit 0
exit 0

You can find these under Builder > Hooks

Pre Tool Use Hook with inline sample starter code.

Each layer holds on its own

The layers stack. Identity is the floor: your RBAC assignments decide what the agent can reach at all. Permissions, the grid and hooks together, decide what it does with a tool. You author each layer, each one holds whether or not the layer above it behaves as expected, and all of it configures through the same ARM and Bicep surface your platform team already uses, reproducible the way the rest of your Azure estate is.

The upgrade path is additive and non-breaking. Existing agents keep working. Turn on each control when you are ready, in the order your governance requires.

There is more coming. We run Azure SRE Agent inside Microsoft on our own production workloads, so we feel the same gaps you do, and the next round is shaped by what we hear from teams running it in production today. Which control is doing the most for you, and which one are you still waiting on? Let us know and thank you!