Type Validators

Type validators check the type and format of values, ensuring data conforms to expected structures.

Type validators generally don’t use transforms since they check data types rather than string content. See Validators Overview for transform documentation.

not_null!

Checks that a value exists and is not null/None.

output:
  not_null!: true

Parameter	Type	Description
value	boolean	`true` to require non-null, `false` to require null

Examples

# Ensure output exists
output:
  not_null!: true

# Ensure tool output exists
get_weather:
  output:
    not_null!: true

# Ensure specific field exists
search_results:
  output:
    items:
      not_null!: true

Use not_null!: true as a first validator to ensure the target exists before applying other validators.

type!

Checks that a value is of a specific type.

output:
  type!: "string"

Parameter	Type	Description
value	string	Type name

Supported Types

Type	Matches
`string`	Strings
`int`	Integers
`float`	Floating-point numbers
`number`	Any numeric type
`bool`	Boolean values
`array`	Lists/arrays
`object`	Dictionaries/objects
`null`	None/null values

Examples

# String output
output:
  type!: "string"

# Numeric result
calculate:
  output:
    type!: "number"

# Array of results
search_products:
  output:
    type!: "array"

# Object response
get_user:
  output:
    type!: "object"

# Boolean flag
validate:
  output:
    type!: "bool"

not_type!

Checks that a value is NOT of a specific type. This is the negated form of type!.

output:
  not_type!: "null"

Parameter	Type	Description
value	string	Type name that must NOT match

Examples

# Ensure output is not null
output:
  not_type!: "null"

# Ensure result is not a string (expect structured data)
process_data:
  output:
    not_type!: "string"

# Ensure not returning an error object
validate:
  output:
    not_type!: "object"

json!

Checks that a string value is valid JSON.

output:
  json!: true

Parameter	Type	Description
value	boolean	`true` to require valid JSON

Examples

# Ensure output is valid JSON
output:
  json!: true

# Combine with content checks
output:
  json!: true
  contains!: '"status"'
  contains!: '"success"'

The json! validator only checks that the string is valid JSON. It does not validate the JSON structure. Use contains! or pattern! for content checks.

email!

Checks that a string value is a valid email format.

extract_email:
  output:
    email!: true

Parameter	Type	Description
value	boolean	`true` to require valid email format

Examples

# Validate extracted email
extract_contact:
  output:
    email:
      email!: true

Common Patterns

Structured Output Validation

output:
  not_null!: true
  type!: "string"
  json!: true
  contains!: '"id"'
  contains!: '"status"'

Type-Safe Numeric Results

calculate:
  output:
    type!: "number"
    gte!: 0
    lte!: 100

Span Output Type Checking

get_datetime:
  output:
    type!: "string"
    pattern!: "^\\d{4}-\\d{2}-\\d{2}"

search_products:
  output:
    type!: "array"
    min_length!: 1

Validating Nested Fields

get_user:
  output:
    type!: "object"
    
# Or validate specific nested fields
get_user:
  output:
    profile:
      name:
        type!: "string"
        not_null!: true
      email:
        email!: true

Getting started

Core Concepts

Agents

Workflows

Human in the Loop

Evals

Deployment

Type Validators

not_null!

type!

Supported Types

not_type!

json!

email!

Common Patterns

Structured Output Validation

Type-Safe Numeric Results

Span Output Type Checking

Validating Nested Fields

​not_null!

​type!

​Supported Types

​not_type!

​json!

​email!

​Common Patterns

​Structured Output Validation

​Type-Safe Numeric Results

​Span Output Type Checking

​Validating Nested Fields

not_null!

type!

Supported Types

not_type!

json!

email!

Common Patterns

Structured Output Validation

Type-Safe Numeric Results

Span Output Type Checking

Validating Nested Fields