CEL Expressions

Devctrl policies use the Common Expression Language (CEL) — a lightweight, fast expression language designed for security policy evaluation. CEL expressions are evaluated on every tool call.

Available variables

Every CEL expression has access to three top-level objects:

identity

Information about the agent making the request.

Variable	Type	Description
`identity.name`	`string`	The identity name (e.g., `"support-agent"`)
`identity.labels`	`map[string, any]`	Key-value labels assigned to the identity

task

Information about the active task session. Only available when the request includes an X-Task-Token header.

Variable	Type	Description
`task.name`	`string`	The task definition name (e.g., `"resolve-ticket"`)
`task.labels`	`map[string, any]`	Key-value labels assigned to the task definition
`task.context`	`map[string, any]`	The runtime context provided when the task session was created

request

Information about the current tool call.

Variable	Type	Description
`request.tool.name`	`string`	The name of the tool being called
`request.tool.args`	`map[string, any]`	The arguments passed to the tool

Operators

CEL supports standard operators:

Operator	Example	Description
`==`	`identity.name == "bot"`	Equality
`!=`	`request.tool.name != "delete"`	Inequality
`&&`	`a == 1 && b == 2`	Logical AND
`\|\|`	`a == 1 \|\| b == 2`	Logical OR
`!`	`!identity.labels.restricted`	Logical NOT
`in`	`request.tool.name in ["a", "b"]`	List membership
`>`, `<`, `>=`, `<=`	`task.context.amount < 1000`	Comparison

String functions

Function	Example	Description
`startsWith()`	`request.tool.name.startsWith("get_")`	String prefix check
`endsWith()`	`request.tool.name.endsWith("_read")`	String suffix check
`contains()`	`request.tool.name.contains("customer")`	Substring check
`matches()`	`request.tool.name.matches("^get_.*")`	Regex match

Map access

Access nested map values using dot notation or index notation:

// Dot notation
identity.labels.team

// Index notation (useful for keys with special characters)
identity.labels["team-name"]

// Check if a key exists using 'has'
has(identity.labels.admin)

Accessing a map key that doesn’t exist causes an error, which results in a deny. Use has() to check for optional keys before accessing them.

Common patterns

Tool names are namespaced as serverName__toolName (e.g., github__list_issues). Use the full namespaced name in your expressions. The examples below use short names for readability.

Allow specific tools

request.tool.name in ["github__get_issue", "github__list_issues", "github__add_comment"]

Check identity labels

identity.labels.team == "engineering"

Scope access by task context

task.context.customer_id == request.tool.args.customer_id

Combine multiple conditions

identity.labels.team == "support"
  && request.tool.name in ["get_issue", "get_customer", "add_comment"]
  && task.context.customer_id == request.tool.args.customer_id

Block dangerous tools

// As a deny rule — blocks these tools for everyone
request.tool.name in ["drop_table", "delete_database", "rm_rf"]

Allow based on optional label

// Check if label exists before reading it
has(identity.labels.admin) && identity.labels.admin == true

Evaluation rules

Deny rules are evaluated first. If any deny rule’s expression returns true, the request is blocked.
Allow rules are evaluated next. If any allow rule’s expression returns false, the request is blocked.
If all rules pass, the request is allowed.
If no active release exists, the project’s default action applies.
If a CEL expression errors (e.g., accessing a missing key), it’s treated as a deny.

Order matters. Place deny rules before allow rules for clear, predictable behavior.

Get Started

Core Concepts

Console Guide

Gateway

Policies

CEL Expressions

Available variables

identity

task

request

Operators

String functions

Map access

Common patterns

Allow specific tools

Check identity labels

Scope access by task context

Combine multiple conditions

Block dangerous tools

Allow based on optional label

Evaluation rules

Next steps

Policy examples

Write policies

​Available variables

​identity

​task

​request

​Operators

​String functions

​Map access

​Common patterns

​Allow specific tools

​Check identity labels

​Scope access by task context

​Combine multiple conditions

​Block dangerous tools

​Allow based on optional label

​Evaluation rules

​Next steps

Policy examples

Write policies

Available variables

identity

task

request

Operators

String functions

Map access

Common patterns

Allow specific tools

Check identity labels

Scope access by task context

Combine multiple conditions

Block dangerous tools

Allow based on optional label

Evaluation rules

Next steps