Awsmux

awsmux

Run one AWS CLI command across your whole fleet in parallel: hundreds of accounts in seconds, safely.

[](LICENSE)

One command fanned out across every account and region at once (100 parallel workers by default, --concurrency raises it), identities verified before anything runs, results merged into one stream. No more shell loops that take a coffee break to crawl the fleet. And anything that mutates is stopped by an approval boundary that even an AI agent with your admin credentials cannot talk its way past. The demo above is a real terminal against the bundled 100-account sandbox fleet; replay it yourself with make fleet-up.

**And it is measurably cheaper and faster for agents. In a 150-session, three-arm benchmark (identical Claude Opus 4.8 agents, identical prompts, same 100-account fleet), the awsmux arm beat a raw-shell aws CLI arm in every cell: 1.3x to 2.9x cheaper, 2.3x to 5.4x faster, a flat 4 turns at every fleet size, and up to 7.4x fewer output tokens (cost and token differences all Holm-adjusted p

Not seeing your profiles? `awsmux doctor` shows exactly which files
were checked, how many profiles each contributed, and whether the aws
CLI and state directory are usable. `awsmux targets` reports where each
profile came from (a `SOURCE` column in table mode, a `source` field in
jsonl: `config`, `credentials`, or `both`).

Useful flags: `--concurrency` (default 100: fleet-wide fan-out is the
point; each in-flight target is one aws CLI subprocess), `--timeout
30s`, `--max-errors N`,
`--stop-on-access-denied`, `--dedupe` (collapse targets that resolve to
the same account, principal, and region), `--output-dir` (one result
file per target),
`--interactive` (checkbox target picker). Every run lands in
`awsmux history` and can be re-run with `awsmux replay`.

## Give it to your AI agent

Two commands, zero configuration:

```sh
go install github.com/0hardik1/awsmux@latest
claude mcp add --scope user awsmux -- awsmux mcp

There is nothing to configure. awsmux mcp serves the agent interface over stdio via the Model Context Protocol: no port, no daemon, no config file, no credentials of its own. It discovers the same profiles your terminal already has (shared config and credentials files; SSO, static keys, and credential_process all pass straight through) and verifies every identity with STS before anything runs. It even locates the aws CLI in well-known install locations when an MCP client spawns it with a bare GUI PATH. Check the connection with /mcp inside Claude Code, then ask the agent "which AWS accounts can you see?" (Drop --scope user to register for the current project only. No Go toolchain? git clone + make build gives you ./bin/awsmux.)

Claude Desktop: Settings > Developer > Edit Config, then add to claude_desktop_config.json (GUI apps do not read your shell PATH, so use the absolute path from which awsmux):

{
  "mcpServers": {
    "awsmux": { "command": "/absolute/path/to/awsmux", "args": ["mcp"] }
  }
}

Other MCP clients (Cursor, Windsurf, Zed, ...): same shape everywhere, a stdio server with command awsmux and args ["mcp"].

The agent gets five structured tools (list_aws_targets, plan_aws_operation, execute_aws_plan, get_aws_execution, cancel_aws_execution) instead of a raw shell, and it uses them on its own: once registered there is nothing to invoke, you just ask ("find every security group open to the world in prod") and the model reaches for the tools automatically. Read-only operations execute freely. Anything else comes back as a plan: the agent hands you a plan ID, you run awsmux approve in your own terminal, and you paste the one-time token back into the chat for the agent to apply. The token binds to the plan's sha256 hash, so the agent cannot alter an approved plan or execute it twice.

Want to watch an agent hit the boundary with zero blast radius? Register the sandbox fleet instead: after make fleet-up, point the server at the fleet's config via environment variables (values printed in .tmp/fleet/env.sh):

claude mcp add awsmux-fleet \
  --env AWS_CONFIG_FILE=$PWD/.tmp/fleet/aws-config \
  --env AWS_SHARED_CREDENTIALS_FILE=$PWD/.tmp/fleet/aws-credentials \
  --env AWSMUX_HOME=$PWD/.tmp/fleet/home \
  -- $PWD/bin/awsmux mcp

The agent gets the 100-account LocalStack fleet over MCP; let it break anything it likes.

The cost and speed numbers in the table at the top come from exactly this setup. One more result from the same benchmark: when an agent was handed both a shell and the MCP tools, it picked awsmux on its own and kept nearly all of the margin.

Safety model

| Class | Examples | Policy | |-------|----------|--------| | read_only | describe-, list-, get-, s3 ls | runs freely | | mutating | create-, put-, update-, s3 cp | --yes, interactive confirm, or approved plan | | destructive | delete-, terminate-, revoke-*, s3 rm | never --yes; typed confirm or plan/approve/apply | | unknown | anything unrecognized | treated as mutating |

Where the verb convention lies, awsmux overrides it: sts calls that mint credentials (assume-role*, assume-root, get-session-token, get-federation-token) and s3api operations that write a local outfile (get-object, get-object-torrent, select-object-content) are classified mutating despite their read-style names.

Stable exit codes for CI and agents: 0 all succeeded, 1 some failed, 2 selection/config error, 3 approval required or rejected, 4 stopped by threshold.

The 03:00 story

A scanner pages: SSH is open to the world somewhere in the fleet. Your agent sweeps 14 verified accounts in one read-only call, finds sg-0a1b2c3d in payments-prod, and proposes the revoke. The revoke is destructive, so the engine hands back a plan instead of running it. You read the plan on your phone: exact command, exact account, verified principal, hash. You approve, paste one token, and go back to sleep while the fix lands in history with the hash attached.

You can replay this exact story against a fleet of fakes right now: make fleet-up.

How it compares

| | awsmux | awsrun | aws-vault / granted / awsume | |---|---|---|---| | Fleet execution across accounts | yes | yes | no (credential tools) | | STS identity preflight per target | yes | no | n/a | | Risk classification + approval boundary | yes | prompt only | n/a | | Agent interface (MCP) | yes | no | no | | 100-account LocalStack test fleet (make fleet-up) | yes | no | no | | History + replay | yes | no | no | | Runtime | single Go binary | Python + plugins | Go / varies |

The credential tools are complementary: awsmux happily executes through profiles they manage.

Docs

• [Architecture](docs/ARCHITECTURE.md): the engine, the plan boundary,

the executor, test-fleet internals.

• [Benchmark](docs/BENCHMARK.md): the agent-cost A/B methodology and

results behind the table above.

Development

make setup                 # git hooks + pre-warm the pinned linter
make build test lint       # or: go build ./... && go vet ./... && go test ./...
make fleet-up e2e          # LocalStack fleet + end-to-end smoke test
make fleet-down clean

CI runs go test and make build on ubuntu and macos, gofmt + go vet, golangci-lint repo-wide, the LocalStack e2e smoke test on ubuntu, and a Conventional Commits check on PR titles (the commit-msg hook enforces the same convention locally).

The demo GIF at the top is a real Ghostty session against the LocalStack fleet, recorded with Kap.

Dependencies: stdlib plus cobra. Roadmap: organization-aware discovery (--ou plus role assumption), policy packs, Homebrew tap and release binaries.

Licensed under [Apache-2.0](LICENSE).

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: 0hardik1
• Source: 0hardik1/awsmux
• License: Apache-2.0

Install and usage instructions live in the source repository linked above.