Head to head · Agent harnesses · October 2026 research run

Agent Zero vs T3 Code

T3 Code scores 51.9 (D) on agent readiness against Agent Zero's 46 (D), and leads in 0 of 7 scored categories. Agent Zero leads on reliability, schema & documentation, security & auth and transparency & trust. Both do agent harnesses.

Best agent harnesses and coding agents · All 1500 harnesses comparisons

Which one, for what

Agent Zero D

Best for A technical owner who wants an agent with its own Linux machine, reachable from Telegram, WhatsApp or email, with scheduled tasks and editable memory.

Ahead on

  • Reliability, 57 against 43
  • Schema & documentation, 64 against 55
  • Security & auth, 54 against 35
  • Transparency & trust, 64 against 51

Watch for

No approval step before shell commands, file changes or outgoing messages. Tool Access defaults to allow

T3 Code D

Best for Developers who want one app, including on their phone, to drive several coding agents they already pay for.

Also in its favour

  • No incidents deducted, where Agent Zero loses 15 points for them

Watch for

Usage data on by default, with hashed OpenAI and Claude account identifiers, and relay traces to Axiom

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Security & auth Agent Zero +19

Agent Zero 54

Harness reading of the framework checklist, the one the Goose calibration dossier uses. 30 for what leaves the machine by default, 20 for approvals and sandboxing, 15 for prompt-injection posture, 15 for audit and 20 for the security programme. No usage telemetry was found in the source. An update check, on by default, posts the version and a 20-character SHA-256 hash of a random per-install id to api.agent-zero.ai. The Update Checker settings page says only that ID and the version are sent and has an off switch. Something still leaves the machine by default, so the partial is kept (22). The agent works inside a Docker container built on Kali Linux and runs as root there. Tool Access can block tools by project or profile and defaults to allow, host access through the A0 CLI is scoped by read, write and execute permissions, and no approval step was found before a shell command, a file deletion or an outgoing message. The web interface has no login until a username is set (10). Infection Check audits the agent's reasoning with a second model before each tool call and ships disabled. Scanners check plugins, skills and MCP servers before install. The channel allow-lists accept every sender when empty, and the email filter matches the claimed From address only, which the plugin README states (7). Chat logs, visible tool steps and Time Travel snapshots, with no per-call audit log. Per-process log files were removed in v2.5 (9). No SECURITY.md on 4 November, security.txt answered 404 on 12 October, and none of the eight CVEs published from 17 March to 22 October 2026 came from the vendor (VulDB, VulnCheck, MITRE and CISA assigned them). A security-review ledger in the repository records two findings, and the v2.12 notes name both fixes (6, a partial kept).

T3 Code 35

Harness reading. Product usage events go by default to ingest.t3.codes and PostHog, with hashed identifiers for your T3 Connect, OpenAI and Claude accounts, and relay traces to Axiom, which can include machine names and error text. Off with T3CODE_TELEMETRY_ENABLED=false or a managed policy. Disclosed in docs/user/telemetry.md, not the README (10 of 30). Permission modes and managed policies (12 of 20). No prompt-injection guidance (5). No audit log (5). No security policy file found (3). 10 + 12 + 5 + 5 + 3 = 35.

Reliability Agent Zero +14

Agent Zero 57

Read with the local-software lines, as software the owner runs. Installs from the agent0ai/agent-zero Docker image, an install script, or a desktop Launcher with builds for macOS, Linux and Windows on x86 and ARM64. The README says it runs wherever Docker runs. The image registry page was not read (17 of 20). The repository holds 245 files under tests/ on 4 November, and its only two workflows still publish Docker images and close inactive issues. The publish workflow runs no tests, so no public CI run shows them passing (5 of 25, a partial kept). 139 open issues and pull requests on 12 October 2026, per that check (GitHub's pages and API weren't read on 4 November). Open reports from September include a crash of run_ui after a failed memory consolidation (#1909), a browser worker that hangs the agent turn (#1923) and truncated backups (#1904), each with no reply or one, and a workflow closes anything inactive for 90 days (11 of 25). Release notes for v2.11, v2.12 and v2.13 carry a Breaking Changes section, but breaking changes ship in minor versions, so the numbering is not semver (9 of 15). v2.15, past 1.0 (15).

T3 Code 43

Local software. An install script and desktop and mobile apps from the vendor (20). ci.yml and windows-tests.yml run on the repository; pass state not read (15). GitHub issues and pull requests weren't read (GitHub's pages refuse these sessions), so that line is scored absent (0). Stable tags v0.1.5 to v0.1.7 with many nightlies, no changelog file (8). Version 0.1.7 (0). 20 + 15 + 0 + 8 + 0 = 43.

Transparency & trust Agent Zero +13

Agent Zero 64

MIT, copyright Agent Zero, s.r.o. (30). No privacy policy for the software was found. The site's cookie notice covers the website, and its terms (14 May 2026) cover the community platform. The docs say where data lives (chats, memory, secrets and settings under /a0/usr) and warn that model providers see what is sent to them only in general terms, with no retention statement (8 of 30). Release notes list breaking changes and removals with the release date, and one deprecated alias is named. No deprecation policy or notice period was found (8 of 20, a partial kept). No usage telemetry was found in the source. The update check is described on its settings page, which says it sends only a randomised, hashed install ID and the version number, and the same page turns it off. The ID is a hash of a random per-install token, a pseudonym under this run's reading, so the statement holds (20). 30 + 8 + 8 + 20 = 66.

T3 Code 51

MIT (30). docs/user/telemetry.md lists what is sent and what isn't, but includes hashed third-party account identifiers and the README doesn't mention it (15 of 30). No deprecation policy (5). Disclosed with an opt-out, on by default (12 of 20). 30 + 15 + 5 + 12 = 62.

Schema & documentation Agent Zero +9

Agent Zero 64

Harness reading of the lines, as the Goose calibration dossier does. No OpenAPI file. The connectivity page lists five external endpoints and the X-API-KEY header, then sends readers to the source or DeepWiki for request and response details. Each API handler and tool has a .dox.md contract file in the repository, and the MCP client JSON shape is documented (10 of 25). llms.txt at www.agent-zero.ai, and AGENTS.md contract files across the repository (10). Guides say which path to use for a need, with tables that separate the browser, the host connector, MCP and A2A (14 of 20). The v2.12 notes say 15 bundled tools gained argument descriptions in non-strict schemas, and plugin settings are typed YAML with commented examples (8 of 15). Guides carry worked examples and a troubleshooting page, with no documented error responses for the external API (9 of 15). Dated notes on every GitHub release and a release article for each version on the site, with no version prefix on API routes (13 of 15).

T3 Code 55

Harness reading. User docs in the repository (managed policy, handoffs, providers, telemetry), AGENTS.md for contributors, a server other clients connect to (55).

Score by category

CategoryWeight this runAgent ZeroT3 CodeEdge
Reliability16%205743Agent Zero +14
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.26455Agent Zero +9
Agent ergonomics13%16.26260Agent Zero +2
Security & auth14%17.55435Agent Zero +19
Payments & pricing10%12.56060even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87575even
Transparency & trust7%8.86451Agent Zero +13
Negative events≤15-150
TotalD 46/100D 51.9/100

Facts side by side

FactAgent ZeroT3 Code
KindAgent harnessAgent harness
VendorAgent Zero, s.r.o.T3 Tools Inc.
Hosted endpointno (local only)no (local only)
Transports
AuthNoneNone
PricingFreeFree
x402nono
LicenceMITMIT
Read-only variant documentednono
llms.txtyesno
Last release2026-11-012026-11-06
Terms last updatedno document linkedno document linked
Privacy policy last updatedno document linkedno document linked
Popularity19k starsnone

How the scores have moved

Verdicts

Agent Zero

Self-hosted under the MIT licence, with seven releases from 12 August to 1 November 2026 and breaking changes listed in minor-release notes. The agent runs shell commands in its container with no approval step, the web interface has no login by default, and eight CVEs from the past year were published by third parties with no vendor advisory.

T3 Code

A fast-moving open-source way to run and steer several coding agents from desktop, browser or phone, using the subscriptions you already have. It's pre-1.0, and it sends usage data by default, including hashed identifiers for your OpenAI and Claude accounts, with the opt-out documented outside the README.

Before you call either

Agent Zero

  1. Set a UI login and password in Settings before publishing the port or opening a tunnel. The default has none
  2. Fill allowed_users, allowed_numbers or sender_whitelist before enabling a channel. An empty list accepts every sender
  3. Enable the Infection Check plugin when the agent reads mail, web pages or MCP results. It ships disabled
  4. Run v2.12 or later. It fixes a Telegram webhook authentication bypass and a WhatsApp media path traversal
  5. Call POST /api_message with the X-API-KEY header. The token changes when the UI login or password changes

T3 Code

  1. Set T3CODE_TELEMETRY_ENABLED=false before starting the server if you don't want usage events sent
  2. Install and log in to at least one provider CLI first, such as codex login or claude auth login
  3. Use a managed policy to fix settings across a team

Questions

Which is better for AI agents, Agent Zero or T3 Code?

T3 Code scores 51.9 (D) on agent readiness against Agent Zero's 46 (D), and leads in 0 of 7 scored categories. Agent Zero leads on reliability, schema & documentation, security & auth and transparency & trust.

Are Agent Zero and T3 Code open source?

Yes. Agent Zero is open source (MIT). T3 Code is open source (MIT).

Other comparisons with Agent Zero or T3 Code

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