Module: MCP::ProtocolDeprecations

Extended by:
ProtocolDeprecations
Included in:
ProtocolDeprecations
Defined in:
lib/mcp/protocol_deprecations.rb

Overview

Warning texts for the features SEP-2577 deprecates at 2026-07-28.

Only the client emits these, from the modern connect, where the capabilities it declares are the ones being deprecated. No server-side trigger remains: the initialize handshake never lands on a deprecating revision and Configuration rejects a modern pin, so nothing on that side can reach a version these apply to. LOGGING_MESSAGE in particular has no caller left (a modern client declares no logging capability, and notify_log_message on that wire is the SEP-2575 sanctioned delivery path rather than a deprecated call). It stays public and callable for embedders, and because deleting it would be a breaking change for no gain.

Constant Summary collapse

ROOTS_MESSAGE = 
"MCP Roots (`roots/list` and `notifications/roots/list_changed`) is deprecated as of protocol version " \
"2026-07-28 (SEP-2577). Use tool parameters, resource URIs, server configuration, or environment " \
"variables instead."
SAMPLING_MESSAGE = 
"MCP Sampling (`sampling/createMessage`) is deprecated as of protocol version 2026-07-28 (SEP-2577). " \
"Use direct LLM provider APIs instead."
LOGGING_MESSAGE = 
"MCP Logging (`logging/setLevel` and `notifications/message`) is deprecated as of protocol version " \
"2026-07-28 (SEP-2577). Use stderr or OpenTelemetry instead."
MESSAGES = 
{
  roots: ROOTS_MESSAGE,
  sampling: SAMPLING_MESSAGE,
  logging: LOGGING_MESSAGE,
}.freeze

Instance Method Summary collapse

Instance Method Details

#deprecated_roots_sampling_logging?(protocol_version) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/mcp/protocol_deprecations.rb', line 35

def deprecated_roots_sampling_logging?(protocol_version)
  return false unless protocol_version

  protocol_version >= Configuration::ROOTS_SAMPLING_LOGGING_DEPRECATED_PROTOCOL_VERSION
end

#warn_for(feature, protocol_version:, uplevel: 1) ⇒ Object 



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# File 'lib/mcp/protocol_deprecations.rb', line 41

def warn_for(feature, protocol_version:, uplevel: 1)
  return unless deprecated_roots_sampling_logging?(protocol_version)

  Kernel.warn(MESSAGES.fetch(feature), uplevel: uplevel)
end

#warn_for_client_capabilities(capabilities, protocol_version:, uplevel: 1) ⇒ Object 



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# File 'lib/mcp/protocol_deprecations.rb', line 47

def warn_for_client_capabilities(capabilities, protocol_version:, uplevel: 1)
  return unless deprecated_roots_sampling_logging?(protocol_version)
  return unless capabilities

  warn_for(:roots, protocol_version: protocol_version, uplevel: uplevel) if capability?(capabilities, :roots)
  warn_for(:sampling, protocol_version: protocol_version, uplevel: uplevel) if capability?(capabilities, :sampling)
end