Content

A content block as used in tool results, prompt messages, and sampling.

Modeled as a tagged union over the per-kind content structs above (TextContent, ImageContent, AudioContent, ResourceLink, EmbeddedResource, ToolUseContent, ToolResultContent). Each kind stores only the fields that are meaningful for it, so there are no meaningless-per-kind fields. Construct via the make* factories; the chainable with* setters apply only on the kinds where the field is valid.

@safe

struct Content {

alias Payload = SumType!(TextContent, ImageContent, AudioContent, ResourceLink, EmbeddedResource, ToolUseContent, ToolResultContent, UnknownContent);

Payload payload;

ContentKind kind();

ResourceContents embeddedResource();

Json annotations();

Json meta();

Content dupSelf();

Content withAnnotations(Json a);

Content withDescription(string d);

Content withTitle(string t);

Content withSize(long s);

Content withContentMeta(Json m);

Content withIsError(bool e);

Content withStructuredContent(Json sc);

static Content makeToolUse(string id, string name, Json input);

static Content makeToolResult(string toolUseId, Content[] content);

Content forVersion(ProtocolVersion v);

}

Members

Aliases

Payload alias Payload = SumType!(TextContent, ImageContent, AudioContent, ResourceLink, EmbeddedResource, ToolUseContent, ToolResultContent, UnknownContent): The underlying tagged union. Public so callers that prefer std.sumtype.match can pattern-match directly over the per-kind structs.

Functions

annotations Json annotations(): The shared annotations value (any kind may carry it).
dupSelf Content dupSelf(): A deep copy of this content block.
embeddedResource ResourceContents embeddedResource(): Decode an embedded resource content block's resource payload into a typed ResourceContents. For the embeddedResource kind this is ResourceContents.fromJson of the raw resource() object (giving typed uri/mimeType/text/blob access instead of the untyped Json); for any other kind it returns a default ResourceContents.
forVersion Content forVersion(ProtocolVersion v): Return a copy of this content block projected for the negotiated protocol version so the wire output stays in-schema for the peer. Two things are projected:
kind ContentKind kind(): Which content kind this block holds.
meta Json meta(): The shared _meta value (any kind may carry it).
withAnnotations Content withAnnotations(Json a): Attach optional annotations (audience/priority/lastModified) to this content block. Returns a copy so calls can be chained, e.g. Content.makeText("hi").withAnnotations(a). Valid on every kind.
withContentMeta Content withContentMeta(Json m): Attach an optional _meta object to this content block. Per the MCP schema every content kind may carry _meta. Returns a copy.
withDescription Content withDescription(string d): Attach an optional description to a resource_link content block, per the MCP ResourceLink shape (it extends Resource). Returns a copy so calls can be chained. Only valid for the resourceLink kind.
withIsError Content withIsError(bool e): Mark a tool_result content block as an error (sampling). Returns a copy. Only valid for the toolResult kind.
withSize Content withSize(long s): Attach an optional size (bytes) to a resource_link content block, per the MCP ResourceLink shape. Returns a copy. Only valid for the resourceLink kind.
withStructuredContent Content withStructuredContent(Json sc): Attach an optional structuredContent object to a tool_result content block (sampling). Returns a copy. Only valid for the toolResult kind.
withTitle Content withTitle(string t): Attach an optional human-readable title to a resource_link content block (ResourceLink extends Resource/BaseMetadata). Returns a copy. Only valid for the resourceLink kind.

Static functions

makeToolResult Content makeToolResult(string toolUseId, Content[] content): A tool_result content block (sampling): the result of a tool call, answering the tool_use whose id is toolUseId. content is the nested result content blocks. Per ToolResultContent in the 2025-11-25 / draft schema.
makeToolUse Content makeToolUse(string id, string name, Json input): A tool_use content block (sampling): the model's request to call a tool. id is the model-assigned call id, name the tool name, and input the arguments object. Per ToolUseContent in the 2025-11-25 / draft schema.