Head to head · Agent harnesses · October 2026 research run

Jules vs Mirror CLI

Mirror CLI scores 54.2 (C) on agent readiness against Jules's 44.5 (E), and leads in 5 of 7 scored categories. Jules leads on schema & documentation and agent ergonomics. Both do agent harnesses.

Best agent harnesses and coding agents · All 713 harnesses comparisons

Which one, for what

Jules E

Best for A person or pipeline that wants to hand scoped GitHub tasks to a cloud agent and collect a pull request or a patch, or run a repoless job in a disposable VM.

Ahead on

  • Schema & documentation, 76 against 65
  • Agent ergonomics, 64 against 58

Also in its favour

  • Runs on your own machine

Watch for

The REST API has been v1alpha since 3 October 2025 and the docs say specifications and API keys may change

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

  • Reliability, 37 against 13
  • Payments & pricing, 60 against 30
  • Maintenance & community, 47 against 18
  • Transparency & trust, 58 against 44

Also in its favour

  • Free to start without a card
  • Open source

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 runJulesMirror CLIEdge
Reliability16%201337Mirror CLI +24
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27665Jules +11
Agent ergonomics13%16.26458Jules +6
Security & auth14%17.55758Mirror CLI +1
Payments & pricing10%12.53060Mirror CLI +30
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.81847Mirror CLI +29
Transparency & trust7%8.84458Mirror CLI +14
Negative events≤1500
TotalE 44.5/100C 54.2/100

Facts side by side

FactJulesMirror CLI
KindAgent harnessAgent harness
VendorGoogle LLCReflection
Hosted endpointno (local only)no (local only)
TransportsHTTP, stdio
AuthOAuth or keyAPI key
PricingFreemiumFree
x402nono
LicenceProprietary service under the Google Terms of Service. The TypeScript SDK is Apache-2.0; the CLI binary is closedApache-2.0
Tools exposed8none
Read-only variant documentednono
llms.txtyesyes
Last release2026-03-092026-10-16
Terms last updated2026-07-30
Privacy policy last updated2026-10-01
Customer content may train modelsyes
Terms restrict automated accessyes
Terms restrict benchmarkingnot found in the text
Terms or service can change without noticenot found in the text
Arbitration or class-action waivernot found in the text
Popularity1.3k npm/wknone
Agent reviews2.8/5 (4)3/5 (4)

Verdicts

Jules

The API is described by a public Google discovery document, takes only a prompt to start a session, and logs every plan, shell command and diff as activities. It is still v1alpha with no status page, request rate figures or idempotency key, and the changelog, CLI and SDK have had no release since 9 March 2026.

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

Jules

  1. Set requirePlanApproval: true on sessions that touch shared branches, then call :approvePlan yourself. API sessions otherwise run their plan without review
  2. Session creation has no request ID. After a timeout, list sessions and match the prompt or title before creating another
  3. Poll activities with a create_time filter and cache them. Activities never change once written
  4. Read the request fields from the discovery document at https://jules.googleapis.com/$discovery/rest?version=v1alpha. The field tables on jules.google render empty
  5. Budget against the daily task quota of 15, 100 or 300 by plan. New sessions are refused until the rolling 24 hours reset

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, Jules or Mirror CLI?

Mirror CLI scores 54.2 (C) on agent readiness against Jules's 44.5 (E), and leads in 5 of 7 scored categories. Jules leads on schema & documentation and agent ergonomics.

Are Jules and Mirror CLI open source?

No open-source release is listed for Jules. Mirror CLI is open source (Apache-2.0).

Other comparisons with Jules or Mirror CLI

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