Module: Hitch::MCP::Protocol

Defined in:

lib/hitch/mcp/protocol.rb

Overview

The MCP protocol vocabulary: the one place that says which version Hitch speaks, which methods it answers, and what a tool may be named.

Plain Ruby in lib rather than app/models, because the public test helper reads it at require time, before Rails has booted.

Constant Summary

VERSION =

"2026-07-28"

METHODS =

Every JSON-RPC method the endpoint answers. Anything else is -32601 before the SDK is built.

%w[server/discover tools/list tools/call].freeze

MAX_TOOL_NAME_LENGTH =

The wire name of a tool, and the shape any tool name must have before it may appear in a telemetry payload or an error report.

64

TOOL_NAME =

/\A[A-Za-z0-9_.-]{1,#{MAX_TOOL_NAME_LENGTH}}\z/

GENERIC_TOOL_ERROR =

The only tool failure text that reaches a client when the host did not author one itself.

"Tool execution failed"

Class Method Summary

• .tool_name?(value) ⇒ Boolean

  instance_of?, not is_a?: a String subclass can override the methods every downstream reader calls, and a tool name reaches telemetry and error reports.

Class Method Details

.tool_name?(value) ⇒ Boolean

instance_of?, not is_a?: a String subclass can override the methods every downstream reader calls, and a tool name reaches telemetry and error reports.

Returns:

• (Boolean)

# File 'lib/hitch/mcp/protocol.rb', line 31

def tool_name?(value)
  value.instance_of?(String) && TOOL_NAME.match?(value)
end