mcplite 0.2.0
- Adds stateless MCP
2026-07-28 support while retaining
initialize-based MCP 2024-11-05, 2025-06-18,
and 2025-11-25. Modern discovery, tool listing, and tool
calls work without initialization; legacy ping behavior is preserved,
while modern ping is unsupported.
- Adds
server/discover with deterministic four-version
ordering. Successful modern results include canonical server identity
and resultType = "complete"; discovery and tool-list
results include public cache hints.
- Expands tool schemas and protocol-native results. Complete
object-root input schemas retain JSON Schema 2020-12 keywords; modern
clients can receive supported output-schema roots and all JSON
structured-content shapes, while older protocols receive compatible
projections and fallback content.
- Adds payload options
mcplite.json.null,
mcplite.json.na, and mcplite.json.auto_unbox,
preserving published defaults and fixed protocol and metadata encoding.
See help("mcplite-results") for configuration details.
- Restores empty structured-root lists as
{} and removes
the unreleased scalar-NA coercion in favor of jsonlite’s class-specific
mappings.
mcplite 0.1.0
- First release of the lightweight, tools-only Model Context Protocol
(MCP) server over standard input and output (stdio), supporting the MCP
lifecycle, ping,
tools/list, and
tools/call.
- Supports protocol versions
2024-11-05,
2025-06-18, and 2025-11-25.
- Provides native tool and JSON Schema helpers, with optional
interoperability for compatible
ellmer tool
definitions.
- Adds explicit protocol-native tool results through
tool_result() and the content_text(),
content_image(), content_audio(),
content_resource_link(), and
content_resource() constructors. Results may contain
ordered mixed content, structured content, annotations, and metadata
while ordinary R return values retain their existing text
conversion.
- Adds object-shaped
output_schema support to
tool(). Tool definitions and results follow the negotiated
MCP version: structured output, output schemas, audio, resource links,
and content metadata are available for 2025-06-18 and
later, with compatible fallback or contained tool errors for
2024-11-05.
- Handles protocol negotiation, request validation, JSON-RPC errors,
and MCP tool-call errors while keeping the stdio protocol stream
usable.
- Automatically traces every envelope-valid MCP operation with one
OpenTelemetry server span, while keeping tool-authored child spans
optional. Standard
otel and otelsdk
configuration owns provider and exporter selection, remote W3C parent
context is accepted through params._meta, and request or
tool content is not captured by default. Stdio servers must use a stderr
or remote exporter because stdout is reserved for MCP messages; with no
exporter configured, tracing is an effective no-op.