Struct McpContent 

pub struct McpContent {
    pub kind: &'static str,
    pub text: String,
    pub mime_type: Option<String>,
    pub uri: Option<String>,
}

Content returned by tool and resource handlers.

Create with McpContent::text (plain text or JSON strings), McpContent::json (marks MIME type as application/json), McpContent::image (base64-encoded binary image data), or McpContent::embedded (a resource embedded inline in a tool response).

Fields

kind: &'static str

"text", "image", "audio", "resource", "blob", "blocks" or "structured".

text: String

The content string — text for "text", base64 data for "image", or the embedded resource’s text for "resource".

mime_type: Option<String>

Optional MIME type override (default "text/plain" for "text"; required in practice for "image"/"resource", set by their constructors).

uri: Option<String>

The resource URI — only set (and only serialized) for "resource".

Implementations

impl McpContent

pub fn text(s: impl Into<String>) -> Self

Plain-text content.

pub fn json(s: impl Into<String>) -> Self

JSON content — sets mimeType to application/json.

pub fn structured(json: impl Into<String>) -> Self

Structured content (MCP 2025-06-18): json is a JSON value — usually an object matching the tool’s McpServer::tool_output_schema — sent as the result’s structuredContent, and as text for older clients.

pub fn audio(data: impl Into<String>, mime_type: impl Into<String>) -> Self

Audio content — data is base64-encoded audio and mime_type e.g. "audio/wav" (MCP 2025-03-26).

pub fn blob(data: impl Into<String>, mime_type: impl Into<String>) -> Self

A binary resource for resources/read — data is base64-encoded and sent as the contents’ blob (with mime_type) instead of text.

pub fn blocks(items: impl IntoIterator<Item = McpContent>) -> Self

Several content items in one tool result — e.g. a text summary, an image and an embedded resource. Each item renders as it would alone.

pub fn input_required(input: InputRequired) -> Self

The tool needs input from the client before it can finish (MCP 2026-07-28 multi round-trip requests): the client answers input’s requests and calls the tool again, with the answers in McpContext::input_response and the state in McpContext::request_state. A client on an earlier protocol version gets a tool error instead.

pub fn image(data: impl Into<String>, mime_type: impl Into<String>) -> Self

Image content (screenshot, chart, generated art) — data is base64-encoded binary and mime_type is e.g. "image/png".

pub fn embedded( uri: impl Into<String>, text: impl Into<String>, mime_type: impl Into<String>, ) -> Self

A resource embedded inline in a tool response, as opposed to one a client fetches separately via resources/read.

Trait Implementations

impl Clone for McpContent

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for McpContent

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

Formats the value using the given formatter.