Enum ContentBlock 

pub enum ContentBlock {
    Text {
        text: String,
        cache_control: Option<CacheControl>,
        citations: Option<Vec<Citation>>,
    },
    Image {
        source: ImageSource,
        cache_control: Option<CacheControl>,
    },
    Document {
        source: DocumentSource,
        title: Option<String>,
        context: Option<String>,
        citations: Option<CitationConfig>,
        cache_control: Option<CacheControl>,
    },
    ToolUse {
        id: String,
        name: String,
        input: Value,
        caller: Option<String>,
        cache_control: Option<CacheControl>,
    },
    ToolResult {
        tool_use_id: String,
        content: Option<ToolResultContent>,
        is_error: Option<bool>,
    },
    Thinking {
        thinking: String,
        signature: Option<String>,
    },
    RedactedThinking {
        data: String,
    },
    SearchResult {
        source: String,
        title: String,
        content: Vec<TextBlock>,
        citations: Option<CitationConfig>,
        cache_control: Option<CacheControl>,
    },
    ServerToolUse {
        id: String,
        name: String,
        input: Value,
        cache_control: Option<CacheControl>,
    },
    WebSearchToolResult {
        tool_use_id: String,
        content: Value,
        cache_control: Option<CacheControl>,
    },
    CodeExecutionToolResult {
        tool_use_id: String,
        content: Value,
        cache_control: Option<CacheControl>,
    },
    ContainerUpload {
        file_id: String,
        cache_control: Option<CacheControl>,
    },
    MidConvSystem {
        content: Vec<TextBlock>,
        cache_control: Option<CacheControl>,
    },
    Unknown {
        block_type: String,
        data: Value,
    },
}

Content block in a message

Known content block types are deserialized into their respective variants. Unrecognized types (e.g., new API features) are captured in ContentBlock::Unknown instead of causing a deserialization error.

Variants

Text

Text content

Fields

text: String

cache_control: Option<CacheControl>

citations: Option<Vec<Citation>>

Citations (appears in responses when using search_result blocks)

Image

Image content

Fields

source: ImageSource

cache_control: Option<CacheControl>

Document

Document content (PDFs, text files)

Requires beta header: anthropic-beta: files-api-2025-04-14

Fields

source: DocumentSource

title: Option<String>

context: Option<String>

citations: Option<CitationConfig>

cache_control: Option<CacheControl>

ToolUse

Tool use request from the assistant

Fields

id: String

name: String

input: Value

caller: Option<String>

Which system invoked this tool (“direct”, “code_execution_20250825”, etc.)

cache_control: Option<CacheControl>

ToolResult

Tool result from the user

Fields

tool_use_id: String

content: Option<ToolResultContent>

is_error: Option<bool>

Thinking

Thinking block from extended thinking

Contains Claude’s step-by-step reasoning process. Appears when extended thinking is enabled.

Fields

thinking: String

signature: Option<String>

RedactedThinking

Redacted thinking block

Contains encrypted thinking that was flagged by safety systems. Must be passed back unmodified in multi-turn conversations.

Fields

data: String

SearchResult

Search result for RAG with automatic citations

Supported in: Opus 4.5, Opus 4.1, Opus 4, Sonnet 4.5, Sonnet 4, Haiku 3.5

Fields

source: String

title: String

content: Vec<TextBlock>

citations: Option<CitationConfig>

cache_control: Option<CacheControl>

ServerToolUse

Server-side tool invocation

Fields

id: String

name: String

input: Value

cache_control: Option<CacheControl>

WebSearchToolResult

Web search tool result

Fields

tool_use_id: String

content: Value

cache_control: Option<CacheControl>

CodeExecutionToolResult

Code execution tool result

Fields

tool_use_id: String

content: Value

cache_control: Option<CacheControl>

ContainerUpload

File uploaded to a container during code execution

Fields

file_id: String

cache_control: Option<CacheControl>

MidConvSystem

System instruction injected mid-conversation

Fields

content: Vec<TextBlock>

cache_control: Option<CacheControl>

Unknown

Unknown content block type (forward compatibility)

When the API returns a content block type this SDK doesn’t recognize, it’s captured here rather than causing a deserialization error.

Fields

block_type: String

The type field value

data: Value

Raw JSON of the unknown block

Trait Implementations

impl Clone for ContentBlock

fn clone(&self) -> ContentBlock

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ContentBlock

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for ContentBlock

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for ContentBlock

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

where __S: Serializer,

Serialize this value into the given Serde serializer.