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Head to head · Agent harness · October 2026 research run

Kiro CLI vs Prime Agent

Prime Agent and Kiro CLI score within a point of each other on agent readiness, 60.5 (C) and 59.9 (C). Kiro CLI leads on schema & documentation and security & auth. Both do agent harness.

Kiro CLIAmazon Web Services · Agent harness C59.9/100#370 of 629 Prime AgentPrime Intellect · Agent harness C60.5/100#352 of 629

Which one, for what

Kiro CLI C

Good for Teams on AWS that want one agent configuration across terminal, IDE and web, with central permission policy, prompt logging to their own S3 bucket and IAM Identity Centre sign-in.

Ahead on

  • Schema & documentation, 79 against 42
  • Security & auth, 66 against 50

Watch for

Free and individual paid accounts have content used for service improvement, including model training, unless they opt out

Prime Agent C

Good for Long-running research and coding work where one model drives subagents, schedules and goals from code, and where the owner can isolate the machine.

Ahead on

  • Reliability, 65 against 57
  • Agent ergonomics, 73 against 67
  • Payments & pricing, 60 against 40
  • Maintenance & community, 79 against 73

Also in its favour

  • No key needed to call it
  • Open source
  • No incidents deducted, where Kiro CLI loses 4 points for them

Watch for

No approval prompts and no sandbox. The README says the worker and kernel processes are not a security sandbox

Score by category

CategoryWeight this runKiro CLIPrime AgentEdge
Reliability16%205765Prime Agent +8
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27942Kiro CLI +37
Agent ergonomics13%16.26773Prime Agent +6
Security & auth14%17.56650Kiro CLI +16
Payments & pricing10%12.54060Prime Agent +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87379Prime Agent +6
Transparency & trust7%8.86764Kiro CLI +3
Negative events≤15-40
Total59.9 · C60.5 · C

Facts side by side

FactKiro CLIPrime Agent
KindAgent harnessAgent harness
VendorAmazon Web ServicesPrime Intellect
Hosted endpointno (local only)no (local only)
Transports
AuthOAuth or keyNone
PricingFreemiumFree
x402nono
LicenceProprietary. Licensed as AWS Content under the AWS Customer Agreement and the AWS Intellectual Property Licence (https://kiro.dev/license/). The GitHub repository is the public issue tracker and doesn't hold the sourceMIT
Read-only variant documentednono
llms.txtyesno
Last release2026-10-052026-10-07
Terms last updated2026-08-14no date given
Privacy policy last updated2026-05-18no date given
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessnot found in the textyes
Terms restrict benchmarkingnot found in the textyes
Terms or service can change without noticenot found in the textyes
Arbitration or class-action waiveryesyes
Popularity4.4k stars22k stars

Verdicts

Kiro CLI

Permission rules follow deny over ask over allow, cloned repositories can't add rules, and a headless session treats every ask as a deny. Content from Free and individual paid accounts is used for service improvement, including model training, unless the user opts out, and API keys for pipelines need a paid plan.

Prime Agent

Budgets for turns, tokens and time bound an autonomous run, and sessions survive a closed terminal through a supervising daemon. Model-written Python and shell commands run with the user's rights, with no approval step and no sandbox, and the Rust build on the main branch ships only as nightly betas.

Before you call either

Kiro CLI

  1. Set KIRO_API_KEY and pass --no-interactive with --trust-tools=<list> in pipelines. Keep --trust-all-tools for disposable environments
  2. Pass --require-mcp-startup when a run depends on MCP tools. Without it a failed server is logged and the run continues
  3. Pass --no-interactive whenever input is piped from a source you don't control, and run 2.10.0 or later on Windows
  4. Run kiro-cli settings telemetry.enabled false and turn off content collection on Free and individual plans. Both are on by default
  5. Export variables in the shell before starting. Since 2.24.0 a project .env file is no longer loaded into sessions, MCP servers or tools

Prime Agent

  1. Run it in a disposable clone, container or VM. It executes model-written Python and shell commands with the user's rights and asks nothing first
  2. Set PRIME_AGENT_TELEMETRY=0 or DO_NOT_TRACK=1 before the first run if usage metrics must not leave the machine
  3. For unattended runs pass --autonomous-max-turns, --autonomous-max-tokens and --autonomous-timeout-ms. Reaching a limit does not mean the task succeeded
  4. Headless use is -p with --mode json per the argument parser. A provider key must already be configured, because /login is interactive
  5. The -t/--tools, -nt/--no-tools and -nbt/--no-builtin-tools flags were removed and now fail as unknown options

Questions

Which is better for AI agents, Kiro CLI or Prime Agent?

Prime Agent and Kiro CLI score within a point of each other on agent readiness, 60.5 (C) and 59.9 (C). Kiro CLI leads on schema & documentation and security & auth.

Are Kiro CLI and Prime Agent open source?

No open-source release is listed for Kiro CLI. Prime Agent is open source (MIT).

Other comparisons with Kiro CLI or Prime Agent

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