MCP::Se...t::Stdio(3)

💅 MCP::Server::Transport::Stdio — the stdio transport for MCP servers

okay so bestie, you're reading the User Contributed Perl Documentation for MCP::Server::Transport::Stdio and honestly? it's giving main character transport energy. let's get into it ✨

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🌸 NAME 🌸

MCP::Server::Transport::Stdio — the stdio transport for MCP servers, periodt.

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🎀 SYNOPSIS 🎀

like, literally just do this:

use MCP::Server::Transport::Stdio;

my $stdio = MCP::Server::Transport::Stdio->new;

slay. that's it. that's the whole setup 🫶

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🦋 DESCRIPTION 🦋

MCP::Server::Transport::Stdio is a transport for an MCP (Model Context Protocol) server, and what it does is: it reads requests from standard input (STDIN) and writes responses to standard output (STDOUT). she's built for command-line tools and debugging tasks, iykyk 💅

here's the tea tho, and you need to hear it: all messages share the one channel. so when a "subscriptions/listen" request comes in, it gets answered with an acknowledgement notification and then it's just… left open 👀 like the JSON-RPC response is withheld until the client cancels it. no cap.

requests are processed strictly in order, which means a "notifications/cancelled" notification cannot be read while the request it refers to is still in flight. so it can only cancel a subscription, that's it, that's all she can do 😭

bestie if you need cancellations to actually work on a running tool, use MCP::Server::Transport::HTTP instead — for workloads where cancelling a running tool matters, that's the one. don't fight the stdio girl about it 🙈

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⭐ ATTRIBUTES ⭐

MCP::Server::Transport::Stdio inherits all attributes from MCP::Server::Transport (she's a nepo baby but make it valid) and implements the following new ones 💖

🍓 subscriptions

my $subscriptions = $stdio->subscriptions;
$stdio            = $stdio->subscriptions({});

this is the registry of active MCP::Server::Subscription objects, keyed by the id of the request that opened them. think of it as the group chat member list but for subscriptions 👑

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🔥 METHODS 🔥

MCP::Server::Transport::Stdio inherits all methods from MCP::Server::Transport and implements the following new ones — she's an overachiever, we love her for it 💜

🌈 handle_requests

$stdio->handle_requests;

reads requests from standard input and prints responses to standard output. literally what it says on the tin, iconic behaviour honestly ✨

🧚 notify_all

my $bool = $stdio->notify_all($method);
my $bool = $stdio->notify_all($method, {foo => 'bar'});

sends a JSON-RPC notification to standard output — once for every subscription in "subscriptions" that asked for it. so if three of your subscriptions asked, three notifications go out. fair's fair 💅

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👑 SEE ALSO 👑

• MCP
• <https://mojolicious.org>
• <https://modelcontextprotocol.io>

go read them, they ate 🫶

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aaaand that's the page bestie! 🎀 this whole thing is running on perl v5.42.0, dated 2026-07-31, and it's the MCP::Se...t::Stdio(3) page — so yes, the footer said the same thing twice, we stan a consistent queen 💖✨