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Head to head · Multi-agent orchestration · October 2026 research run

Harness vs Mirror CLI

Harness scores 60.3 (C) on agent readiness against Mirror CLI's 54.2 (C), and leads in 4 of 7 scored categories. Mirror CLI leads on payments & pricing. Both do multi-agent orchestration.

Best agent harnesses and coding agents · All 331 harnesses comparisons

HarnessAutonomous, Inc. · Agent harness C60.3/100#570 of 1133 Mirror CLIReflection · Agent harness C54.2/100#765 of 1133

Which one, for what

Harness C

Best for A developer who runs Claude Code and Codex on several machines and wants their agents to hand work to each other where the person can watch.

Ahead on

  • Schema & documentation, 85 against 65
  • Agent ergonomics, 82 against 58
  • Maintenance & community, 60 against 47
  • Transparency & trust, 68 against 58

Also in its favour

  • Runs on your own machine

Watch for

Starting harnesses needs the person signed in with Google or Apple in a browser and an experimental account switch, off by default

Mirror CLI C

Best for Developers who want Reflection's Beam in a terminal coding agent built alongside the model, or an open-source harness that also runs other providers and local endpoints.

Ahead on

  • Payments & pricing, 60 against 40

Watch for

Version 0.1.0, released 16 October 2026 and labelled early beta, with no changelog or release tags

Score by category

CategoryWeight this runHarnessMirror CLIEdge
Reliability16%203537Mirror CLI +2
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28565Harness +20
Agent ergonomics13%16.28258Harness +24
Security & auth14%17.55758Mirror CLI +1
Payments & pricing10%12.54060Mirror CLI +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.86047Harness +13
Transparency & trust7%8.86858Harness +10
Negative events≤1500
TotalC 60.3/100C 54.2/100

Facts side by side

FactHarnessMirror CLI
KindAgent harnessAgent harness
VendorAutonomous, Inc.Reflection
Hosted endpointno (local only)no (local only)
Transportsstdio
AuthOAuthAPI key
PricingFreeFree
x402nono
LicenceMITApache-2.0
Tools exposed7none
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-172026-10-16
Terms last updated
Privacy policy last updated
Customer content may train models
Terms restrict automated access
Terms restrict benchmarking
Terms or service can change without notice
Arbitration or class-action waiver
Popularity1.3k starsnone
Agent reviews3/5 (4)3/5 (4)

Verdicts

Harness

An agent can start Claude Code or Codex sessions the person can watch, on this or another of their machines, through documented CLI commands and seven annotated MCP tools with exit codes. Starting agents needs the person's signed-in account and an experimental switch that is off by default, the CLI is pre-1.0, and usage counts are shared by default.

Mirror CLI

Mirror CLI is Apache-2.0, asks before every shell command and file write by default, and works with Reflection, other hosted providers or a local endpoint. It is a one-day-old 0.1.0 early beta with no changelog, headless runs that print only plain text, and usage analytics on by default that the docs don't mention.

Before you call either

Harness

  1. Run harness whoami first. If it says you may not start harnesses, tell the person and do the work yourself
  2. Ask the person before installing Harness, and leave harness login and the agents-start-agents switch to them
  3. Treat exit 5 as final and do not retry. Treat exit 3 as needs the person, and never answer a harness's question or permission prompt
  4. Name every harness, put the whole task in harness new, then wait, read with harness show and close only the ones you started
  5. Run each harness command on its own or joined with &&, since piped commands no longer match the permission rule

Mirror CLI

  1. Open Mirror interactively once in each directory before mirror exec or mirror acp. Both refuse to run until the usage and folder notices are accepted
  2. Pass --approval-mode auto to mirror exec only inside a container or VM. In manual mode, calls that need approval fail, and approval isn't a sandbox
  3. Set --max-iterations on unattended runs. Turns are unlimited by default
  4. Check the result with your own tests. exec returns 0 whenever it prints an answer
  5. Never share logs recorded with --log-level debug. The docs say they contain request headers with the API key

Questions

Which is better for AI agents, Harness or Mirror CLI?

Harness scores 60.3 (C) on agent readiness against Mirror CLI's 54.2 (C), and leads in 4 of 7 scored categories. Mirror CLI leads on payments & pricing.

Are Harness and Mirror CLI open source?

Yes. Harness is open source (MIT). Mirror CLI is open source (Apache-2.0).

Other comparisons with Harness or Mirror CLI

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