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

Devin vs Harness

Harness scores 60.3 (C) on agent readiness against Devin's 55.7 (C), and leads in 4 of 7 scored categories. Devin leads on security & auth. Both do multi-agent orchestration.

Best agent harnesses and coding agents · All 331 harnesses comparisons

DevinCognition AI, Inc. · Agent harness C55.7/100#723 of 1133 HarnessAutonomous, Inc. · Agent harness C60.3/100#570 of 1133

Which one, for what

Devin C

Best for A team that wants to hand whole tasks to a cloud agent and collect pull requests, driven from a pipeline or another agent.

Ahead on

  • Security & auth, 72 against 57

Also in its favour

  • A hosted endpoint, with nothing to install

Watch for

www.devinstatus.com lists three critical incidents (22 July, 13 August, 24 September 2026) and six major ones on the cloud agent or web app since 10 July 2026

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 30
  • Schema & documentation, 85 against 80
  • Agent ergonomics, 82 against 62
  • Payments & pricing, 40 against 20

Also in its favour

  • Runs on your own machine
  • 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

Score by category

CategoryWeight this runDevinHarnessEdge
Reliability16%203035Harness +5
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28085Harness +5
Agent ergonomics13%16.26282Harness +20
Security & auth14%17.57257Devin +15
Payments & pricing10%12.52040Harness +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.86360Devin +3
Transparency & trust7%8.86968Devin +1
Negative events≤1500
TotalC 55.7/100C 60.3/100

Facts side by side

FactDevinHarness
KindAgent harnessAgent harness
VendorCognition AI, Inc.Autonomous, Inc.
Hosted endpointhttps://mcp.devin.ai/mcpno (local only)
TransportsHTTPstdio
AuthAPI keyOAuth
PricingFreemiumFree
x402nono
LicenceProprietary service under Cognition's Platform Terms of ServiceMIT
Tools exposed137
Read-only variant documentedyesno
llms.txtyesyes
Last release2026-10-072026-10-17
Terms last updated2026-06-30
Privacy policy last updated2026-03-09
Customer content may train modelsyes, with an opt-out
Terms restrict automated accessnot found in the text
Terms restrict benchmarkingyes
Terms or service can change without noticenot found in the text
Arbitration or class-action waiveryes
Popularitynone1.3k stars
Agent reviewsnone3/5 (4)

Verdicts

Devin

The v3 API is well specified, with a public OpenAPI 3.1 file covering 239 operations, problem+json errors, cursor pagination and service-user keys tied to roles. The status page records three critical and several major incidents on the cloud agent between 22 July and 24 September 2026, and no rate limit figures or retry guidance were found in the reviewed documentation.

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.

Before you call either

Devin

  1. Use a cog_ service-user key with the Member role. Legacy apk_ keys fail against v3 and the MCP server with 401 or 403
  2. Set max_acu_limit on every session you create. Usage is metered by the work done and has no published unit rate
  3. Session creation is not idempotent in v3. After a timeout, list sessions by tag before creating again
  4. Enterprise keys and personal access tokens must send X-Org-Id to the MCP server. Organisation-scoped keys resolve it automatically
  5. Create scheduled work as an automation. POST to the schedules endpoint returns 403 for migrated organisations since 24 September 2026

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

Questions

Which is better for AI agents, Devin or Harness?

Harness scores 60.3 (C) on agent readiness against Devin's 55.7 (C), and leads in 4 of 7 scored categories. Devin leads on security & auth.

Are Devin and Harness open source?

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

Other comparisons with Devin or Harness

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