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Construct protocol-native MCP content blocks

Source: R/tool_result.R
content-blocks.Rd

These constructors create the only content-block objects accepted by tool_result(). All R-facing names use snake_case; MCP names such as mimeType and _meta are created only when a result is serialized.

Usage

content_text(text, annotations = list(), meta = list())

content_image(data, mime_type, annotations = list(), meta = list())

content_audio(data, mime_type, annotations = list(), meta = list())

content_resource_link(
  uri,
  name,
  title = NULL,
  description = NULL,
  mime_type = NULL,
  size = NULL,
  annotations = list(),
  meta = list()
)

content_resource(
  uri,
  text = NULL,
  blob = NULL,
  mime_type = NULL,
  annotations = list(),
  meta = list()
)

Arguments

text

A single text string. For content_resource(), the resource text payload; exactly one of text or blob must be supplied.

annotations

Optional named MCP annotations. Known R-facing fields are audience, priority, and last_modified; named extension fields are preserved when serializable.

meta

Optional named outer content-block metadata. For content_resource(), metadata is not duplicated into the inner resource contents object.

data

A scalar base64 string containing inline image or audio data.

mime_type

A single MIME type string. Optional for resources and resource links.

uri

A single non-empty author-supplied resource URI.

name

A single non-empty resource-link name.

title

Optional resource-link display title.

description

Optional resource-link description.

size

Optional non-negative whole-number resource size in bytes.

blob

A scalar base64 string containing an embedded resource payload; exactly one of text or blob must be supplied.

Value

A validated content block for use in tool_result().

Details

Image, audio, and resource blob data must already be scalar base64 strings. The constructors do not read files, download URLs, infer MIME types, encode, decode, or validate base64 data, or invent resource URIs. Tool authors own payload integrity, accurate MIME types, meaningful URIs, authorization, sanitization, and payload size decisions.

Resource links only transport an author-supplied URI. mcplite remains a tools-only server and does not make that URI readable or implement resources/read. Embedded resources are self-contained content blocks.