# Authorize LangChain agent tool calls with Cerbos

Control which tools your LangChain agents can invoke with fine-grained, policy-driven authorization powered by Cerbos.

### Tool authorization

Control which LangChain tools each user or role can invoke with fine-grained Cerbos policies

### Context-aware decisions

Authorize tool calls based on user identity, roles, attributes, and request context at runtime

### Audit every tool call

Every authorization decision is logged with full context, giving you a complete audit trail of agent behavior

## How Cerbos works with LangChain

AI agents and tools introduce a new class of authorization challenges. They act on behalf of users, access sensitive data, and chain operations, all of which need fine-grained access control.

Cerbos provides policy-driven authorization that controls what AI systems can do, which data they can access, and on whose behalf. Policies are written in human-readable YAML and evaluated at request time.

With Cerbos and LangChain, you get guardrails that scale with your AI adoption, centrally managed policies, full audit trails, and sub-millisecond decision times that don't slow down agent workflows.

### How Cerbos authorizes LangChain tool calls

1. **Define policies for tool access**, Write YAML policies that specify which tools each user or role can invoke based on identity, attributes, and context.
2. **Agent requests authorization before each tool call**, Before invoking a tool, the LangChain agent sends the user context, tool name, and target resource to the Cerbos PDP.
3. **Cerbos evaluates the request against policies**, The PDP applies fine-grained rules considering the user's identity, role, and any additional attributes you provide.
4. **Tool call proceeds or is blocked**, Cerbos returns an allow or deny decision. The agent framework enforces it, with every decision logged for audit.

### Security risks of unsecured AI agents

Without authorization at every tool call, AI agents introduce risks that traditional application security doesn't cover:

- **Privilege escalation through tools.** An agent with unrestricted tool access can perform actions the delegating user isn't authorized for — reading sensitive data, modifying resources, or invoking admin operations.
- **Incomplete identity context.** Agents often carry only a partial user reference. Without the full profile, policies can't enforce department-level, role-based, or attribute-based restrictions accurately.
- **No audit trail.** Without authorization checks at each step, there's no record of what the agent did, on whose behalf, or why it was allowed — making incident investigation and compliance reporting impossible.
- **Transitive trust.** When agents chain tool calls or delegate to other agents, permissions can expand silently if each step isn't individually authorized.

### Richer agent decisions with Cerbos Synapse

When an AI agent makes an authorization call on behalf of a user, it often includes only an agent ID or partial user reference. [Cerbos Synapse](/content/product-cerbos-synapse/index.html) enriches these requests with the full user profile from your identity provider, resource metadata from your data stores, and the agent's own constraints — so the PDP receives complete context for every decision without the agent needing to assemble it.

## FAQ

### How does Cerbos authorize LangChain tool calls?

Before a LangChain agent invokes a tool, it sends the user context, tool name, and target resource to the Cerbos PDP. Cerbos evaluates fine-grained policies and returns an allow or deny decision, ensuring agents only use tools the requesting user is authorized for.

### Can I control tool access per user or role?

Yes. Cerbos policies are attribute-based, so you can restrict tool access by role, department, subscription tier, or any other context you provide. Policies are written in YAML and managed outside your application code.

### Does this work with LangGraph?

Yes. Cerbos integrates at the tool-call boundary, so it works with both standard LangChain agents and LangGraph workflows. Each tool invocation is individually authorized.

## Cerbos + LangChain

- Cerbos policies govern AI agent tool access and data visibility
- Full audit trail for every AI tool call and data access
- Per-user permissions enforced across autonomous agent workflows
- Sub-millisecond policy evaluation with no agent pipeline overhead