Module name 

Decoding the Mcp-Name header value.

Mcp-Name mirrors params.name (a tool or prompt name) or params.uri (a resource URI). Tool names are only SHOULD-constrained to header-safe characters and URIs are not constrained at all, so the spec defines a sentinel escape: a value that cannot ride in an ASCII header field arrives as

Mcp-Name: =?base64?{Base64EncodedValue}?=

The markers are lowercase and case-sensitive, and the payload is Base64 over the UTF-8 bytes using the standard alphabet (the spec’s own example =?base64?PT9iYXNlNjQ/bGl0ZXJhbD89?= contains /, so it is not URL-safe Base64).

This matters to a meter for one blunt reason: the price book is keyed on tool name. Matching =?base64?...?= against it does not merely fail to find the tool, it silently prices every non-ASCII-named tool at the default rate. The spec requires servers and intermediaries that inspect these values to “decode them accordingly” before comparing.

Clients MUST also encode any plain-ASCII value that happens to look like the sentinel, so decoding is unambiguous: anything wearing the markers is encoded.

Enums

NameError

Why a Mcp-Name value could not be decoded.

Constants

SENTINEL_PREFIX

Opening marker of the Base64 sentinel form.

SENTINEL_SUFFIX

Closing marker of the Base64 sentinel form.

Functions

decode

Decode a raw Mcp-Name header value to the name the body actually carries.

encode

Encode a value into the sentinel form. Test and client-side helper.

is_sentinel

Whether a raw header value is wearing the complete Base64 sentinel.