Module: Ask::MCP::XMcpHeader

Defined in:
lib/ask/mcp/x_mcp_header.rb

Overview

Validation of x-mcp-header annotations in tool inputSchemas (2026-07-28, SEP-2243).

Servers MAY designate tool parameters to be mirrored into HTTP headers via an x-mcp-header extension property. Clients using the Streamable HTTP transport MUST reject a tool definition whose annotations violate the constraints below (rejection = exclude the tool from tools/list); clients on other transports (stdio, SSE) MAY ignore the annotations.

Constant Summary collapse

TOKEN_RE =

RFC 9110 field-name token characters (1*tchar).

/\A[!#$%&'*+\-.^_`|~0-9A-Za-z]+\z/
PRIMITIVE_TYPES =

Primitive types that may carry an x-mcp-header annotation.

%w[string integer boolean].freeze
JS_SAFE_MIN =

JavaScript safe integer range.

-(2**53) + 1
JS_SAFE_MAX = 
2**53 - 1

Class Method Summary collapse

Class Method Details

.invalid_reason(schema) ⇒ Object

Returns the reason the tool definition's x-mcp-header annotations are invalid, or nil if the definition is valid (or has no annotations).



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# File 'lib/ask/mcp/x_mcp_header.rb', line 26

def invalid_reason(schema)
  seen = {}
  find_invalid(schema, seen, tainted: false)
end

.safe_integer?(value) ⇒ Boolean

Whether an integer value is representable as a safe header value.

Returns:

  • (Boolean) 


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# File 'lib/ask/mcp/x_mcp_header.rb', line 32

def safe_integer?(value)
  value.is_a?(Integer) && value.between?(JS_SAFE_MIN, JS_SAFE_MAX)
end