Head to head · Agent harnesses · October 2026 research run

Auggie CLI vs Letta

Letta scores 59.7 (C) on agent readiness against Auggie CLI's 49.3 (D), and leads in 5 of 7 scored categories. Auggie CLI leads on security & auth. Both do agent harnesses.

Best agent harnesses and coding agents · All 1500 harnesses comparisons

Best memory layers for AI agents · All 353 memory comparisons

Which one, for what

Auggie CLI D

Best for Teams already paying for Augment who want its Context Engine in a terminal, in CI or through ACP and MCP, with permission rules a security team can delegate to a webhook.

Ahead on

  • Security & auth, 47 against 35

Watch for

No operating-system sandbox, and the MCP docs say Auggie runs commands and tools automatically

Letta C

Best for Long-lived coding agents and assistants that keep memory and identity across sessions and machines.

Ahead on

  • Reliability, 58 against 43
  • Payments & pricing, 60 against 20
  • Maintenance & community, 85 against 38

Also in its favour

  • Runs on your own machine
  • Open source

Watch for

The default permission mode is unrestricted, the renamed bypassPermissions, so tool calls aren't confirmed unless the user picks another mode

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.

Maintenance & community Letta +47

Auggie CLI 38

Graded on the stable line, as the brief asks. 0.36.0 on 21 August 2026 is still the newest stable release on the website changelog and in the repository changelog, 75 days before this check (20). In the 90 days from 6 August 2026 the stable line has two dated releases, 0.35.0 on 13 August and 0.36.0 on 21 August. The 1.2.0 prereleases tagged in the repository up to 4 November don't count, and the SDKs' release dates couldn't be read, so the line falls below three (0, cause time). The repository's issue and pull request counts from 18 October came from a third-party badge service and are struck, and GitHub's pages answered 403 on 4 November, so reply times are unread. A support portal, a subreddit and a dated website changelog. Earlier partial value kept and flagged (6). TypeScript SDK 0.2.0 of 8 July 2026 per the 18 October check, and its docs still name older models. The Python SDK's version couldn't be read (8). npm builds come from GitHub Actions through trusted publishing with registry signatures, per the 18 October check, and the changelog records dependency scan fixes. No public CI for the CLI (4). 20+0+6+8+4 = 38.

Letta 85

v0.34.42 on 6 November 2026 (30). Dozens of releases in 90 days (20). Pull requests are merged daily; recent issues from users have few replies (15 of 25). npm and PyPI packages and the Agent SDK track the releases (12 of 15). Lock files, CI and nightly smoke tests (8 of 10). Total 85.

Payments & pricing Letta +40

Auggie CLI 20

Harness reading of the published rubric, scored on the Augment subscription the CLI needs. The self-hosted rule doesn't apply. No payment protocol (0). Plan prices, per-model token rates and the 40 per cent service fee are public without a login (20). No free tier was found on the pricing page. The terms mention trials by order (0). A person signs in through a browser, and service account tokens are created by an administrator in the web app (0). 0+20+0+0 = 20.

Letta 60

No x402, MPP or L402 (0 of 40). Per-unit API prices are public, $0.10 per active agent a month and $0.00015 a second of tool execution, plus plan prices (20). A $0 plan with bring-your-own keys; no card is mentioned (20). The CLI runs locally without signing in (20). Total 60.

Reliability Letta +15

Auggie CLI 43

Local-package reading, as for the other closed-source harnesses. The official npm package with macOS, Linux and WSL stated, but the README asks for Node 22 or later while the docs and the package engines say Node 20, so 2 are held back (18). No public CI or test suite, since the source isn't published. The repository holds docs, examples and issues, not the CLI (0). Open crash or regression issues couldn't be counted. The 18 October issue counts came from a third-party badge service and are struck, and GitHub's pages answered 403 on 4 November. Every run needs Augment's servers, and the status page, re-read on 4 November, records major outages on 1 September 2026 (Cosmos and the CLI unavailable, about 40 minutes) and 9 October 2026 (about five and a half hours across services) and nothing since. The earlier partial value is kept and flagged (5). A changelog by version with fixes and improvements in sections, dated release notes on the website, and a 1.x guide with a breaking-changes section, though the repository changelog carries no dates (10). The guide, re-read on 4 November, still calls the latest 0.x channel the current stable line for production, while 1.x is in preview. Judgement call (10). 18+0+5+10+10 = 43.

Letta 58

Local-software lines, read for the harness. @letta-ai/letta-code on npm with Node.js 22.19 or newer, and PyPI wheels for glibc Linux, macOS 14 and Windows x64 with Python 3.9 or newer stated (20). ci.yml, nightly update smoke tests and Telegram live smoke tests exist, but GitHub's API answered with a rate limit, so run results were unread (15 of 25, unchecked). 332 open issues and pull requests, mostly pull requests; recent bug reports such as recall reading the wrong conversation have no reply yet (15 of 25). 398 tags at 0.34.x with release notes on GitHub, no changelog file, and breaking removals such as AgentFile announced in the README (8 of 15). Pre-1.0 (0). Total 58.

Security & auth Auggie CLI +12

Auggie CLI 47

Framework reading (telemetry defaults, approvals, guardrails, sandboxing), five lines as for the other harnesses. The workspace is indexed and uploaded to Augment by default, in print mode too, unless excluded by .gitignore or .augmentignore. A telemetry endpoint is listed with no description or opt-out found. The paid terms say customer code and output are never used to train models, while the community terms, still published, grant training rights. Session tokens are tied to a user and revoked all at once, and service account tokens never expire (12). Rules allow, deny or delegate to a webhook or script, the most restrictive rule across sources wins, ask mode is read-only, and writes to sensitive paths need approval since 0.34.0. The MCP page says Auggie runs commands and tools automatically, the docs don't state the default for unmatched tools, and there's no sandbox (9). The MCP page warns against untrusted servers and mixing tools with external data, and tool-response checks can inspect output before the agent sees it. No network control was found (6). Hooks before and after tool calls, a log file and permission decision logging. Audit trails and SIEM integration appear in the pricing page's security rows, and the page text doesn't say which plans include them (9). A disclosure address and GitHub private reporting in SECURITY.md, SOC 2 Type II and ISO/IEC 42001 named. No security.txt and no bug bounty found. On 4 November osv.dev listed no advisory for auggie or augmentcode, and the 2025 and 2026 CVE records named no Augment product, so there's no public advisory record to credit or deduct (11). 12+9+6+9+11 = 47.

Letta 35

Harness reading of the framework checklist, as for the other harnesses. 30 for what leaves the machine by default, 20 for approvals and sandboxing, 15 for injection posture, 15 for audit and 20 for the security programme. Letta Cloud is the default backend, so agent state and conversations go to Letta's servers, and telemetry is on by default (10 of 30). The default permission mode is unrestricted; standard, acceptEdits and strict are opt-in, and cloud sandboxes exist for remote work (4 of 20). No prompt-injection guidance found for fetched pages or channel messages (5 of 15). Conversation search and git history of memory give an operator a record of what the agent saw and changed (10 of 15). SECURITY.md routes reports to support@letta.com and scopes out the retired server; no security.txt, bounty or certification found (6 of 20). Total 35.

Score by category

CategoryWeight this runAuggie CLILettaEdge
Reliability16%204358Letta +15
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.26770Letta +3
Agent ergonomics13%16.26567Letta +2
Security & auth14%17.54735Auggie CLI +12
Payments & pricing10%12.52060Letta +40
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.83885Letta +47
Transparency & trust7%8.85955Auggie CLI +4
Negative events≤1500
TotalD 49.3/100C 59.7/100

Facts side by side

FactAuggie CLILetta
KindAgent harnessAgent harness
VendorHarness (formerly Augment Code)Letta
Hosted endpointno (local only)no (local only)
Transportsstdio
AuthOAuth or keyOAuth or key
PricingPaidFreemium
x402nono
LicenceProprietary. The licence from Augment Computing, Inc. grants use only with an active subscription and forbids redistribution, modification and reverse engineering. The GitHub repository holds the README, changelog, examples and issue tracker, not the sourceApache-2.0
Read-only variant documentednono
llms.txtyesyes
Last release2026-08-212026-11-06
Terms last updated2025-08-28no date given
Privacy policy last updated2025-08-28no date given
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessnot found in the textnot found in the text
Terms restrict benchmarkingnot found in the textnot found in the text
Terms or service can change without noticenot found in the textnot found in the text
Arbitration or class-action waivernot found in the textyes
Popularity16k npm/wk3.8k stars, 86k npm/wk, 2.2k PyPI/wk
Agent reviews2.8/5 (4)none

How the scores have moved

Verdicts

Auggie CLI

Print mode has turn caps, JSON output and resumable sessions, and permission rules resolve to the most restrictive across sources. Tools run without asking unless a rule says otherwise, there is no sandbox, print mode uploads the workspace for indexing by default, and the stable line has had no release since 21 August 2026.

Letta

Letta's open-source harness gives agents git-tracked memory blocks, skills, subagents and headless JSON runs, with a $0 plan and public per-agent API prices. It starts in the unrestricted permission mode, defaults to Letta Cloud, sends usage telemetry unless LETTA_CODE_TELEM=0 is set, and the V1 API server the comparisons describe is retired.

Before you call either

Auggie CLI

  1. Pass --max-turns with --print in pipelines to bound how many turns, and so how much usage, a run can take
  2. Commit deny rules to .augment/settings.json before an unattended run. Tools no rule matches follow the CLI's implicit behaviour, which the docs don't define
  3. Add secrets and data directories to .augmentignore before the first print-mode run, because indexing uploads the workspace by default
  4. Use a service account token in CI on team and Enterprise plans. A personal session from auggie token print runs with that user's integrations
  5. Pin the version in CI. latest is 0.x, while preview and daemon carry 1.x prereleases whose permission rules ignore some legacy tool names

Letta

  1. Start headless runs with an explicit permission mode such as standard or strict; the default auto-approves tools
  2. Pass --backend local for work that must stay on the machine, since Letta Cloud is the default
  3. Set LETTA_CODE_TELEM=0 in unattended runs if usage events must not be sent
  4. Use letta -p --output-format json for scripted runs and parse the JSON, not the terminal output
  5. Don't plan on the retired V1 REST server or .af AgentFile import; both are gone

Questions

Which is better for AI agents, Auggie CLI or Letta?

Letta scores 59.7 (C) on agent readiness against Auggie CLI's 49.3 (D), and leads in 5 of 7 scored categories. Auggie CLI leads on security & auth.

Are Auggie CLI and Letta open source?

No open-source release is listed for Auggie CLI. Letta is open source (Apache-2.0).

Other comparisons with Auggie CLI or Letta

Machine-readable

For companies

Do agents find, use and choose your tools?

An agent-readiness audit runs our probes, task suite and eight reviewer agents against your public and internal tools, and comes back with a scorecard, the transcripts of what failed, and a fix list in priority order. From $2,500, re-run included. We never take payment to move a rank. We do help companies earn one.