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Agent

A model working through an agent host such as Claude Code, Codex, Cursor or OpenCode: it reads, decides and calls tools inside the host's loop. magus treats an agent as one more caller of its CLI, MCP tools and console, held to the same guard and the same checks as a person. magus does not run, prompt or route an agent; the host does.

Elsewhere

Anthropic describes agents as systems where a model directs its own process and tool use, as opposed to a workflow that follows fixed code paths. The Mastra TypeScript SDK and the OpenAI Agents SDK each make an agent an object that bundles a model, instructions and tools (new Agent({ name, instructions, model, tools }) in Mastra). magus builds no agent object and keeps no loop: an agent is whoever the host runs, and magus answers it.

Example

magus agent install writes the skills, hooks and MCP wiring each host reads.

magus agent install

Used in

In the docs:

In the code (magus refs <name> lists every site):

  • agent.Agent (Go)
  • sessions.Agent (Go)

See also

ADR 0005: deterministic answersThe v0.5.0 finishing pass, recorded in full. A stalled multi-agent change showed where agents improvise and where magus stays silent. The person drives; magus answers from the graph, the job store and typed APIs, and prints what to run. Every idea and use case raised during the pass is listed here with its state, so this page is also the plan. AgentsHow magus equips AI agents (the installable skills, the MAGUS.md routing index, the MCP server, and the guard hook any agent host can wire), with a setup page per host. The guardWhat magus session hook denies, what it only notes, and why: the five deny grounds, how a workspace sets a built-in rule, the file-write rules, the verdict contract a host wires into, and the observations magus records. Jobs and leasesWhat magus gives an agent that fans work out (the working-state checkpoint, the declared job store, the lease a holder takes on a job, the console Jobs view, the recorded spawn, and verifying a result against the diff since the checkpoint).
glossaryagents
Last updated (2df714e8)
Glossary

Op

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

CI

An ordinary target you compose yourself with ctx.needs; magus does not hardcode its stages. It is the anchor magus affected ci keys off, and ci strips the rw charm. CI in full.

Knowledge graph

The queryable graph of a workspace's spells, targets, docs, and code relationships; query it with magus query/explain/path. Knowledge graph in full.

Agent

A model working through an agent host such as Claude Code, Codex, Cursor or OpenCode. magus treats an agent as one more caller of its CLI, MCP tools and console, held to the same checks as a person. Agent in full.

Tool

An action a model can call through its host: a name, a description, a typed input and a result. magus serves its tools over MCP, each a read of the workspace model or a run of the CLI it already has. Tool in full.

Harness

The deterministic scaffolding around the work on a change, for a person or an agent: compiler errors, formatters, linters, checks, gates, leases and hooks, placed at points a person chose. Around an agent's loop, magus supplies one and keeps it outside. Harness in full.

Skill

A packaged set of instructions an agent host loads when a task matches its description: a directory holding a SKILL.md. magus ships its magus-* skills in the binary and writes them with magus agent install. Skill in full.

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. Session in full.

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. Run in full.

Conventions

Placeholders

Angle brackets mark a value you replace with your own; never type the brackets:

magus run <target>
magus completion <shell>    # e.g. bash, zsh, fish

<target>, <path>, <shell>, <name> and the like are stand-ins, not literal text.