MCP::Se...::Legacy(3)

📦 version 0.150.0, in opensuse-leap 16.0

💅 MCP::Se...::Legacy(3) — the perl manpage, but make it cute

okay so bestie, welcome to the User Contributed Perl Documentation for MCP::Server::Legacy 💖 this is the little fallback module that keeps the old-protocol girlies connected while everyone else upgrades. let's get into it ✨

🌸 NAME 🌸

MCP::Server::Legacy — the fallback for clients that are still speaking a previous protocol version 🫶 like, no cap, it's the group chat translator for the old heads.

🦋 SYNOPSIS 🦋

use MCP::Server::Legacy qw(legacy_request);

my $version = legacy_request('2025-11-25', {jsonrpc => '2.0', id => 1, method => 'tools/call'});

that's it, that's the whole vibe check 🔥 you import legacy_request and you're literally off to the races.

🎀 DESCRIPTION 🎀

so here's the tea ☕ MCP::Server::Legacy answers the "initialize" handshake of clients speaking a protocol revision older than PROTOCOL_VERSION in MCP::Constants. the whole point? so they can still list and call tools, prompts and resources while the ecosystem catches up. iconic, honestly 👑

but bestie, listen — nothing beyond that is supported. in particular:

  • no notifications 🚫
  • no multi round-trip requests 🚫

it's giving temporary convenience, and it will be removed again in a future release 💀 so don't get too attached, iykyk.

✨ FUNCTIONS ✨

MCP::Server::Legacy implements the following functions, which can be imported individually 🧚

🌈 legacy_context

my $context = legacy_context($params, $context);

populate an MCP::Server::Context with the values a current request would have carried in "_meta" 💜 lowkey just filling in the blanks so everything lines up.

⭐ legacy_request

my $version = legacy_request($version, $request);

returns the protocol revision a request was made with, or undef if it is not legacy — based on the "MCP-Protocol-Version" header and the JSON-RPC request 🔍

here's the important part, bestie: a request carrying "_meta.io.modelcontextprotocol/protocolVersion" is never legacy, whatever the header says. so a current client with a misconfigured header still gets a proper error — we love a graceful fail 💅

also! revisions before "2025-06-18" predate the header, so a request without one is assumed to be legacy. yes, we're just assuming, don't come for us 🙈

💀 legacy_result

my $result = legacy_result($server, $method, $version);

the result for a "initialize" or "ping" request, or undef for every other method 👀 the handshake echoes the requested protocol revision and advertises the same primitives as "server/discover", but never "listChanged" — because list change notifications are not supported. periodt. 🎯

🍓 SEE ALSO 🍓

bestie reminder: this is a temporary convenience module, so if you're out here building your whole personality on it, maybe diversify your portfolio 💜

and that's the whole page, no notes ✨ this was perl v5.42.0, dated 2026-07-31, and it's the MCP::Se...::Legacy(3) manpage signing off — slay, stay legacy-safe, mwah 💅💖

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