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magus-mcp

Serve MCP over stdio for the agent host that launched it

Synopsis

magus mcp

Description

Serve MCP over stdin and stdout, one JSON-RPC message per line, for the agent host that launched this process. It opens the workspace it is launched in and needs no server and no bearer token: the caller is the local process the host started, admitted with mcp=write, and every tool call is recorded on the activity trail with the stdio credential and the client's name.

Stdout is the protocol wire and carries nothing else; logs and one line saying what is being served go to stderr. It stops when the host closes stdin, or on Ctrl+C.

Register it with an MCP client as a stdio server:

command magus args ["mcp"]

magus server start serves the same tools over Streamable HTTP for one long-lived server shared by several clients; that endpoint takes a connector token (magus config mcp connector create). A target this process runs asks the broker for host capacity like any other run.

Per-client configuration lives in docs/guides/integrations/mcp.md, not in this binary: naming a client here would make a change to its config format a magus release.

Exit status

0
The host closed stdin.
1
The workspace did not load, or reading stdin or writing stdout failed.
2
An argument was given; mcp takes none.

See Also

magus(1), magus-ls(1), magus-describe(1), magus-run(1), magus-x(1), magus-where(1), magus-affected(1), magus-graph(1), magus-query(1), magus-explain(1), magus-path(1), magus-refs(1), magus-watch(1), magus-events(1), magus-status(1), magus-clean(1), magus-shell(1), magus-vcs(1), magus-queue(1), magus-doctor(1), magus-config(1), magus-session(1), magus-memory(1), magus-job(1), magus-notes(1), magus-diff(1), magus-server(1), magus-broker(1), magus-buzz(1), magus-completion(1), magus-man(1), magus-init(1), magus-spell(1), magus-agent(1), magus-self(1), magus-version(1)

ManpagePages in this section. magus brokerCheck or stop the broker: the per-user process that holds this host's concurrency slots, declared memory and shared services, which a run starts on its own. magus selfManage the magus binary in place, with a self-update subcommand supporting version pinning, dry-run, downgrade, and out-of-tree install directories, plus registry data refresh and the mgs shorthand. ChangelogEvery change to magus, newest first, in Keep a Changelog format, starting with the unreleased entries. Generated from changes/unreleased/ and releases/*.yaml.
generatedinternal/cli/registry.goclimagus mcpmcpagentstdio
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Glossary

Workspace

The magus root directory that owns a set of projects and shared config; the unit magus operates over. See workspace.

Target

A named operation (build, test, ...) you invoke with magus run <target>; it may compose a spell's tool-native operations and depend on other targets. See targets.

Op

A single tool-native command a target composes (long form: operation); the middle of the work hierarchy (Spell to Op to Target). See operations.

Spell

A language/runtime adapter (e.g. go, md) that maps generic targets onto a toolchain's real commands. See spells.

Buzz

The language magusfiles are written in (the .buzz engine). See engines.

Affected

The set of projects touched by a change; magus affected <target> runs a target only over them. See affected.

Broker

The per-user background process that holds this host's capacity: the machine budget every run claims slots from, and the shared services runs keep warm. A run starts it on demand; broker: off in magus.yaml runs without one. See server.

Server

The background process a person starts with magus server start. It serves MCP, the console, background jobs and the warm knowledge graph, and adopts nested magus calls into one pool. See server.

CI

An ordinary magusfile-defined target you compose yourself with magus\needs - magus does not hardcode its stages. Magus.RunCI treats it specially only in that it strips the rw charm, it is the anchor magus affected ci keys off, and a selected scope with no project declaring it is a load error rather than a silent no-op. See targets.

MAGUS.md

The committed routing index at a workspace root, regenerated from the knowledge graph: it lists every node and points at the exact query for a given question, so it is the entry point an agent reads first. See knowledge.

Session

An agent host's conversation, by the id the host delivers to its hooks. magus never mints one: a record with no session is unattributed, and the OS user it carries says whose account ran it.

Job

The unit of delegated work, and one row of the job store: what an orchestrating agent handed out, with its goal, the checkpoint it was cut against, the paths it may write or must not touch, and the one check it runs. A job's holder is either a session, for work an orchestrator handed out, or the server, for its own maintenance. The store records; the agent guard is what reads those facts back when grading a write. See doctrine.

A job is not a run. magus run build web is a run, and no job exists for it. A job causes runs: its check executes as one, and a server job records the invocation of its last one. Jobs are listed with magus ls jobs and in the console's Jobs view; runs are listed in the Runs view.

Run

One target executing under one magus invocation, such as magus run test web or magus affected ci. A run keeps its captured output behind an output reference. Every magus run is a run whether or not any job asked for it; see Job for how the two relate.

Lease

The grant a holder takes on a job: the write and read paths that job declared, enforced in the checkout that took it with magus job exec. A job is the piece of work; a lease is permission over it.

Conventions

This page uses none of the site's convention markers. The full set is on the conventions page.