Struct CustomTool 

pub struct CustomTool {
    pub name: String,
    pub description: String,
    pub input_schema: Value,
    pub disable_user_input: Option<bool>,
    pub input_examples: Option<Vec<Value>>,
    pub cache_control: Option<CacheControl>,
    pub defer_loading: Option<bool>,
    pub eager_input_streaming: Option<bool>,
    pub strict: Option<bool>,
}

Custom client-side tool definition

Defines a tool with a name, description, and JSON Schema for its inputs. Claude can call this tool and the client handles execution.

Example

use claude_sdk::CustomTool;
use serde_json::json;

let tool = CustomTool::new(
    "get_weather",
    "Get weather for a location",
    json!({
        "type": "object",
        "properties": {
            "location": { "type": "string" }
        },
        "required": ["location"]
    }),
)
.programmatic();

Fields

name: String

description: String

input_schema: Value

disable_user_input: Option<bool>

If true, Claude will use this tool programmatically without asking the user

input_examples: Option<Vec<Value>>

Example inputs for the tool (beta feature)

Requires beta header: anthropic-beta: advanced-tool-use-2025-11-20 Each example must be valid according to the input_schema.

cache_control: Option<CacheControl>

Cache control for this tool definition

defer_loading: Option<bool>

Defer loading this tool until needed

eager_input_streaming: Option<bool>

Stream tool inputs as they’re generated

strict: Option<bool>

Enable strict JSON schema validation

Implementations

impl CustomTool

pub fn new( name: impl Into<String>, description: impl Into<String>, input_schema: Value, ) -> Self

Create a new custom tool definition

pub fn programmatic(self) -> Self

Set programmatic tool calling (no user confirmation)

pub fn with_strict(self) -> Self

Enable strict JSON schema validation

Trait Implementations

impl Clone for CustomTool

fn clone(&self) -> CustomTool

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CustomTool

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for CustomTool

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<CustomTool> for ToolDefinition

fn from(tool: CustomTool) -> Self

Converts to this type from the input type.

impl Serialize for CustomTool

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.