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

Harness vs Jules

Harness scores 60.3 (C) on agent readiness against Jules's 44.5 (E), and leads in 6 of 7 scored categories. Both do multi-agent orchestration.

Best agent harnesses and coding agents · All 713 harnesses comparisons

HarnessAutonomous, Inc. · Agent harness C60.3/100#573 of 1146 JulesGoogle LLC · Agent harness E44.5/100#1000 of 1146

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

  • Reliability, 35 against 13
  • Schema & documentation, 85 against 76
  • Agent ergonomics, 82 against 64
  • Payments & pricing, 40 against 30
  • Maintenance & community, 60 against 18
  • Transparency & trust, 68 against 44

Also in its favour

  • Free to start without a card
  • Open source

Watch for

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

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.

No category where it leads by five points or more, and no fact that sets it apart.

Watch for

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

Score by category

CategoryWeight this runHarnessJulesEdge
Reliability16%203513Harness +22
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28576Harness +9
Agent ergonomics13%16.28264Harness +18
Security & auth14%17.55757even
Payments & pricing10%12.54030Harness +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.86018Harness +42
Transparency & trust7%8.86844Harness +24
Negative events≤1500
TotalC 60.3/100E 44.5/100

Facts side by side

FactHarnessJules
KindAgent harnessAgent harness
VendorAutonomous, Inc.Google LLC
Hosted endpointno (local only)no (local only)
TransportsstdioHTTP, stdio
AuthOAuthOAuth or key
PricingFreeFreemium
x402nono
LicenceMITProprietary service under the Google Terms of Service. The TypeScript SDK is Apache-2.0; the CLI binary is closed
Tools exposed78
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-172026-03-09
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 stars1.3k npm/wk
Agent reviews3/5 (4)2.8/5 (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.

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.

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

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

Questions

Which is better for AI agents, Harness or Jules?

Harness scores 60.3 (C) on agent readiness against Jules's 44.5 (E), and leads in 6 of 7 scored categories.

Are Harness and Jules open source?

Harness is open source (MIT). No open-source release is listed for Jules.

Other comparisons with Harness or Jules

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