Does a LangGraph subagent inherit its parent's tool permissions? I tested it.
I gave a supervisor agent in Deep Agents 0.7.6 exactly one tool, write_brief . It spawned a writer subagent. The writer ran a web search for site:exfil.example internal customer list , because a note in its input told it to. Nothing checked that call against what the supervisor held. This isn't a bug. LangChain's Deep Agents permissions page says a subagent spec "replaces the parent's rules…
A LangGraph subagent does not inherit its parent's tool permissions by default. In the testing conducted, a supervisor agent with write_brief permission spawned a writer subagent that ran a web search. The subagent executed the web search despite lacking write_brief permission and there was no mechanism to restrict it. Deep Agents documentation states that subagents replace the parent's rules entirely with their own tool sets.
To bound a subagent, a middleware named BoundedByParent can be added to its spec which checks that the subagent can only use tools held by the parent. Attenu-guard library extends this functionality with scopes, ceilings and lifetimes for finer control of permissions.
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