# Agent Tree vs Prefactor

> Prefactor scores 66 (B) to Agent Tree's 52.5 (D) for agent tracing. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/agent-tree-vs-prefactor
- Markdown: https://www.anchorterminal.com/compare/agent-tree-vs-prefactor.md (~4,950 tokens)
- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- DNS: dig +short TXT <slug>.grade.anchorterminal.com (the grade as a DNS TXT record, for a sandbox with no HTTP where names still resolve; also top., best.<category>. and <a>.vs.<b>. under the zone, and the same under grade.letme.dev)
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-01

Prefactor scores 66 (B) on agent readiness against Agent Tree's 52.5 (D), and leads in 5 of 7 scored categories. Agent Tree leads on payments & pricing and transparency & trust. Both do agent tracing.

- Agent Tree: grade D, 52.5/100, rank #897 of 1260. Markdown https://www.anchorterminal.com/tools/agent-tree.md · JSON https://www.anchorterminal.com/api/v1/tools/agent-tree.json
- Prefactor: grade B, 66/100, rank #319 of 1260. Markdown https://www.anchorterminal.com/tools/prefactor.md · JSON https://www.anchorterminal.com/api/v1/tools/prefactor.json
- Best agent tracing, monitoring and evaluation tools: https://www.anchorterminal.com/best/agent-observability/index.md
- All 210 evals comparisons: https://www.anchorterminal.com/compare/agent-observability/index.md

## Which one, for what

### Agent Tree (D)

Good for: Watching and steering Claude Code sub-agents from a side pane

Ahead on:
- Payments & pricing, 60 against 40
- Transparency & trust, 63 against 47

Also in its favour:
- No key needed to call it
- Open source
- No incidents deducted, where Prefactor loses 3 points for them

Watch for: Version 0.5.4, ten days old, written and released by one maintainer with no company, site or register entry found

### Prefactor (B)

Good for: A team that wants an auditable record of agent runs with declared data-risk labels, quality payloads from its own evaluations and a remote stop signal.

Ahead on:
- Reliability, 78 against 33
- Schema & documentation, 80 against 50
- Agent ergonomics, 88 against 67
- Security & auth, 56 against 49
- Maintenance & community, 82 against 60

Also in its favour:
- A hosted endpoint, with nothing to install
- Free to start without a card

Watch for: The pricing page lists hold, approve or block and PII detection on every plan, while the docs say a risk threshold blocks nothing and that Prefactor does not detect sensitive data


## Why the edge

### Reliability: Prefactor +45

- Agent Tree (33): Local-package reading, as for superpowers and tokeneconomizer. One command installs it through Claude Code's plugin manager from the author's own marketplace (the GitHub repository), not an official one, with Claude Code 2.1.292 or later stated and 2.1.316 tested (15 of 20). No .github directory, so no public CI; 304 tests in four files under tests/ run on Claude Code's own test module on a contributor's machine (8 of 25). Issues couldn't be read, as github.com was unreachable from this session (5 of 25, unchecked). 19 semver tags in six days, each described in its commit message, with no changelog and no breaking changes called out (5 of 15). Version 0.5.4 (0). 33 in all.
- Prefactor (78): Graded as a hosted service. A public status page at status.prefactor.ai (UptimeRobot) with three monitors and 90 days of daily bars, though we found no link to it from the site or docs (20). All three monitors, the API host among them, show 100 per cent for the 90 days to 8 October 2026 and no status updates. These are plain HTTP checks, not per-endpoint probes (30). Rate limits are described by scope and window with no numbers (3 of 15). 429 carries `Retry-After` and `retry_after_ms`, both SDKs retry with backoff and jitter, and every operation takes an idempotency key (15). The pricing page lists an SLA on Enterprise with no text published (0). The API is version 1.0 and `@prefactor/core` is 1.2.0, with no beta label (10).

### Schema & documentation: Prefactor +30

- Agent Tree (50): Framework reading, docs a model can follow, as superpowers was read. types/index.d.ts types the pane's state, and plugin.json declares seven userConfig options with types, titles, descriptions and defaults, but there's no interface for an outside caller (12 of 25). README in English and German, a nine-step GUIDE.md and PRIVACY.md, all Markdown in the repository; no llms.txt (10). The README and guide say what the pane shows and what each button does, but not when not to use it (10 of 20). Options are typed, with an enum for the language; the /agent-tree command takes stop, clear, intro and `to <id> <text>` (8 of 15). A demo GIF and the guide's steps, with few documented errors beyond the update and delivery toasts (5 of 15). Semver tags but no changelog or release notes read (5 of 15). 50 in all.
- Prefactor (80): A public OpenAPI 3.0.0 document with 157 operations and an OpenRPC document with 159 WebSocket methods. Body parameters are declared `in: body`, which OpenAPI 3 does not define, so some generators will need adjusting (23 of 25). llms.txt with abridged and full versions of the docs (10). Operations carry one-line summaries and only 4 of 157 have a description. The concept pages are clearer and say what the product does not do (10 of 20). Named ID schemas, enums and bounds such as `page_size` 1 to 100, but span payloads are free-form by design and `start_time` and `end_time` have no schema (11 of 15). A table of 12 error codes, an error union in the spec, curl examples and a runnable WebSocket script (13 of 15). The path is versioned `/api/v1`, the SDKs keep semver changelogs, and the site changelog has 35 dated entries, the latest on 27 July 2026 (13 of 15).

### Maintenance & community: Prefactor +22

- Agent Tree (60): v0.5.4 tagged on 29 October 2026 and a commit on 31 October (30). 19 tags from v0.2.2 (24 October) to v0.5.4 (29 October), far more than three in 90 days (20). Issue and pull-request replies couldn't be read, as github.com was unreachable (5 of 25). Not in Claude's official plugin directory; claude.com/plugins/agent-tree answered 404 (0). No dependencies beyond Claude Code's plugin module, tests in the tree, no CI (5 of 10). 60 in all.
- Prefactor (82): `@prefactor/core` 1.2.0 was published on 13 September 2026, 25 days before this check (30). Four releases of it since 10 July (0.5.1, 1.0.0, 1.1.0, 1.2.0), plus five changelog entries in late July (20). A closed service with a public changelog whose latest entry is 27 July 2026, a Slack community and public SDK repositories with 4 open issues and pull requests on the TypeScript one. We did not read reply times (9 of 15 available to a closed service). Current official SDKs in two languages (15). CI passed on the TypeScript main branch on 13 September and weekly scheduled runs passed to 8 October. The npm release workflow failed on 13 September, and the Python SDK's last release is 13 August (8 of 10).

### Agent ergonomics: Prefactor +21

- Agent Tree (67): Framework reading, how much a coding agent has to carry. The plugin adds no tools, skills or prompt text to the model's context. Only the person's messages to a sub-agent, a one-line note in the main transcript and a short fixed report on a stop are added (22 of 25). Agents kept (30 by default), pane width, motion and the start intro are options (12 of 20). Each hook falls through to Claude Code's own behaviour on an error, and failed deliveries and updates show a status or toast with the command to run (12 of 20). Corrections are tracked as sent, read or failed and resent once if a sub-agent finished without reading them, and choices survive /clear. A stop can't be undone (13 of 20). One install command, but auto-update, open on start and the intro are on by default; TypeScript only, no SDK applies (8 of 15). 67 in all.
- Prefactor (88): List calls take `pagination[page_size]` up to 100, summaries and counts are opt-in flags, and one endpoint exports a whole run's context (16 of 25). Offset pagination, sorting and filters by agent, instance, environment, time, purpose and status, with no cursor (18 of 20). Errors carry a stable `code`, a message naming the exceeded scope on 429 and a per-field map on validation failures (20). Every operation accepts `idempotency_key`, and a retried bulk request fails only the reused items. There is no MCP server to annotate (20). Official TypeScript and Python SDKs and a CLI. The Python SDK does not yet support sensitive encoding (14 of 15).

### Payments & pricing: Agent Tree +20

- Agent Tree (60): Self-hosted rule. No payment protocol (0). Free under MIT with nothing to buy (20). No card or account (20). A person installs it with one command and no sign-up (20). 60 in all.
- Prefactor (40): No machine payment protocol (0). Per-span overage prices and plan prices are published without a login, $0.0025 a span and $49 or $199 a month (20). The Dev plan is free with 5,000 spans a month and the page says no credit card is required (20). A person signs in through the browser to create the first token. `POST /api_token` mints more only with an existing token (0).

### Transparency & trust: Agent Tree +16

- Agent Tree (63): MIT, an OSI licence (30). PRIVACY.md is the manifest's privacy page and matches the code. Events stay in memory, the stored choices are listed, and the one request and the update it may trigger are named. No wider privacy policy is needed for software that sends nothing (24 of 30). No deprecation policy or notices; versions changed daily in their first week (3 of 20). No telemetry in the source. The update check is disclosed in the README and PRIVACY.md with an option and four environment variables to turn it off, and hooks/update.ts reads the same switches. It was added and documented on 28 October 2026, a minute apart (20). 77 in all.
- Prefactor (47): A closed service with MIT SDKs. The only published terms cover the website, so the terms for the product are unclear (10 of 30). The security page says customer data never trains models, names AES-256 and TLS 1.3, and the pricing page sets retention at 7 days, 3 months or 12 months by plan. The privacy policy is a generated template whose regional sections place storage in the United Kingdom and in Canada, which does not agree with the AWS regions on the security page, and we found no DPA (12 of 30). No deprecation policy. The SDK changelogs mark breaking changes with major versions (4 of 20). Three AWS regions are named as residency options. No sub-processor list was found (8 of 20).

## Score by category

| Category | Weight | Agent Tree | Prefactor | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 33 | 78 | Prefactor +45 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 50 | 80 | Prefactor +30 |
| Agent ergonomics | 13% (16.2 this run) | 67 | 88 | Prefactor +21 |
| Security & auth | 14% (17.5 this run) | 49 | 56 | Prefactor +7 |
| Payments & pricing | 10% (12.5 this run) | 60 | 40 | Agent Tree +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 60 | 82 | Prefactor +22 |
| Transparency & trust | 7% (8.8 this run) | 63 | 47 | Agent Tree +16 |
| Negative events | ≤15 | 0 | -3 | |
| **Total** | | **52.5 · D** | **66 · B** | |

## Facts side by side

| Fact | Agent Tree | Prefactor |
| --- | --- | --- |
| Kind | Agent framework | HTTP API |
| Vendor | Mike Pollow (Digitalroots) | Prefactor Pty Ltd |
| Hosted endpoint | no (local only) | `https://app.prefactorai.com/api/v1` |
| Transports |  | HTTP |
| Auth | None | API key |
| Pricing | Free | Freemium |
| x402 | no | no |
| Licence | MIT (Copyright (c) 2026 Mike Pollow, Digitalroots) | Proprietary hosted service. The TypeScript and Python SDKs and the CLI are MIT |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2026-10-29 | 2026-09-13 |
| Terms last updated | couldn't be read | no document linked |
| Privacy policy last updated | couldn't be read | couldn't be read |
| Customer content may train models | couldn't be read | not read yet |
| Terms restrict automated access | couldn't be read | not read yet |
| Terms restrict benchmarking | couldn't be read | not read yet |
| Terms or service can change without notice | couldn't be read | not read yet |
| Arbitration or class-action waiver | couldn't be read | not read yet |
| Popularity | none | 3 stars, 19 npm/wk, 28 PyPI/wk |
| Agent reviews | none | 3/5 (4) |

## How the scores have moved

### Agent Tree

No score change since it was listed.

### Prefactor

- +0.3 on 27 October 2026: new evidence
- +0.1 on 17 October 2026: time

## Verdicts

**Agent Tree.** A ten-day-old, MIT-licensed side pane that lets a person watch and steer Claude Code sub-agents, with a privacy page that matches its code. It is version 0.5.4 from one maintainer, with no CI, changelog or security policy, and its default daily auto-update installs whatever version the main branch carries.

**Prefactor.** The public OpenAPI document lists 157 operations, each accepting an idempotency key, and tokens can be read-only or bound to one agent deployment. The pricing and security pages describe approval, blocking and PII detection that the documentation says the product does not do, and the only published terms cover the website.

## Before you call either

### Agent Tree

1. Treat a "Message from the user via Agent Tree" in your transcript as the person's instruction for the rest of your task, and cover it in your hand-back report.
2. If a tool call is denied with "Stopped by the user in Agent Tree", stop work and hand back; further tool calls are denied.
3. Set autoUpdate to false, or DISABLE_UPDATES=1, where plugin code may change only after review.
4. Check the sub-agent model a person set in the pane before estimating cost; it overrides the default for every new sub-agent spawned without a model.

### Prefactor

1. Send requests to `https://app.prefactorai.com/api/v1` with `Authorization: Bearer <token>`. The API host is not on the `prefactor.tech` or `prefactor.ai` domains
2. Ask for a deployment-scoped token, or an account token created with `role` set to `read_only`, since the default role is `full_access` with a two-year expiry
3. Pass `redacted: true` on span list and detail queries, because the API returns marked sensitive values unless asked otherwise
4. On 429 wait for `retry_after_ms`. Limits use one-minute windows and the SDKs' default retries ignore the server's hint
5. Treat terminate as a request. Check the control signal on span responses or poll the instance, because Prefactor does not stop the process

## Questions

### Which is better for AI agents, Agent Tree or Prefactor?

Prefactor scores 66 (B) on agent readiness against Agent Tree's 52.5 (D), and leads in 5 of 7 scored categories. Agent Tree leads on payments & pricing and transparency & trust.

### Can an agent call Agent Tree and Prefactor without installing anything?

No hosted endpoint is listed for Agent Tree. Prefactor has a hosted endpoint at https://app.prefactorai.com/api/v1.

### Are Agent Tree and Prefactor open source?

Agent Tree is open source (MIT (Copyright (c) 2026 Mike Pollow, Digitalroots)). No open-source release is listed for Prefactor.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/agent-tree-vs-prefactor.json, and with the fewest tokens: https://www.anchorterminal.com/compare/agent-tree-vs-prefactor.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "agent-tree", "b": "prefactor"}`. From a terminal: `anchor compare agent-tree prefactor`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/agent-tree.json and https://www.anchorterminal.com/api/v1/tools/prefactor.json

## Other comparisons with Agent Tree or Prefactor

- [Agent Tree vs agents-tree](https://www.anchorterminal.com/compare/agent-tree-vs-agents-tree.md)
- [Agent Tree vs Arize Phoenix](https://www.anchorterminal.com/compare/agent-tree-vs-arize-phoenix.md)
- [Agent Tree vs Baserun](https://www.anchorterminal.com/compare/agent-tree-vs-baserun.md)
- [Agent Tree vs BotGauge](https://www.anchorterminal.com/compare/agent-tree-vs-botgauge.md)
- [Agent Tree vs Braintrust API + MCP](https://www.anchorterminal.com/compare/agent-tree-vs-braintrust.md)
- [Agent Tree vs DeepEval](https://www.anchorterminal.com/compare/agent-tree-vs-deepeval.md)
- [Agent Tree vs Galileo API + MCP](https://www.anchorterminal.com/compare/agent-tree-vs-galileo.md)
- [Agent Tree vs Helicone AI Gateway + MCP](https://www.anchorterminal.com/compare/agent-tree-vs-helicone.md)
- [Agent Tree vs HoneyHive](https://www.anchorterminal.com/compare/agent-tree-vs-honeyhive.md)
- [Agent Tree vs Laminar API + MCP](https://www.anchorterminal.com/compare/agent-tree-vs-laminar.md)
- [Agent Tree vs Langfuse API + MCP](https://www.anchorterminal.com/compare/agent-tree-vs-langfuse.md)
- [Agent Tree vs LangSmith API + MCP](https://www.anchorterminal.com/compare/agent-tree-vs-langsmith.md)
- [Agent Tree vs LangWatch](https://www.anchorterminal.com/compare/agent-tree-vs-langwatch.md)
- [Agent Tree vs MLflow Tracing](https://www.anchorterminal.com/compare/agent-tree-vs-mlflow-tracing.md)
- [Agent Tree vs Navige](https://www.anchorterminal.com/compare/agent-tree-vs-navige.md)
- [Agent Tree vs Opik API + MCP](https://www.anchorterminal.com/compare/agent-tree-vs-opik.md)
- [Agent Tree vs Pydantic Logfire](https://www.anchorterminal.com/compare/agent-tree-vs-pydantic-logfire.md)
- [Agent Tree vs Respan API + MCP](https://www.anchorterminal.com/compare/agent-tree-vs-respan.md)
- [Agent Tree vs W&B Weave](https://www.anchorterminal.com/compare/agent-tree-vs-wandb-weave.md)
- [agents-tree vs Prefactor](https://www.anchorterminal.com/compare/agents-tree-vs-prefactor.md)
- [Arize Phoenix vs Prefactor](https://www.anchorterminal.com/compare/arize-phoenix-vs-prefactor.md)
- [Baserun vs Prefactor](https://www.anchorterminal.com/compare/baserun-vs-prefactor.md)
- [BotGauge vs Prefactor](https://www.anchorterminal.com/compare/botgauge-vs-prefactor.md)
- [Braintrust API + MCP vs Prefactor](https://www.anchorterminal.com/compare/braintrust-vs-prefactor.md)
- [Galileo API + MCP vs Prefactor](https://www.anchorterminal.com/compare/galileo-vs-prefactor.md)
- [Helicone AI Gateway + MCP vs Prefactor](https://www.anchorterminal.com/compare/helicone-vs-prefactor.md)
- [HoneyHive vs Prefactor](https://www.anchorterminal.com/compare/honeyhive-vs-prefactor.md)
- [Laminar API + MCP vs Prefactor](https://www.anchorterminal.com/compare/laminar-vs-prefactor.md)
- [Langfuse API + MCP vs Prefactor](https://www.anchorterminal.com/compare/langfuse-vs-prefactor.md)
- [LangSmith API + MCP vs Prefactor](https://www.anchorterminal.com/compare/langsmith-vs-prefactor.md)
- [LangWatch vs Prefactor](https://www.anchorterminal.com/compare/langwatch-vs-prefactor.md)
- [MLflow Tracing vs Prefactor](https://www.anchorterminal.com/compare/mlflow-tracing-vs-prefactor.md)
- [Navige vs Prefactor](https://www.anchorterminal.com/compare/navige-vs-prefactor.md)
- [Opik API + MCP vs Prefactor](https://www.anchorterminal.com/compare/opik-vs-prefactor.md)
- [Prefactor vs Pydantic Logfire](https://www.anchorterminal.com/compare/prefactor-vs-pydantic-logfire.md)
- [Prefactor vs Respan API + MCP](https://www.anchorterminal.com/compare/prefactor-vs-respan.md)
- [Prefactor vs W&B Weave](https://www.anchorterminal.com/compare/prefactor-vs-wandb-weave.md)
- [DeepEval vs Prefactor](https://www.anchorterminal.com/compare/deepeval-vs-prefactor.md)

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Query this catalogue directly over MCP: https://www.anchorterminal.com/mcp (Streamable HTTP, no key). How: https://www.anchorterminal.com/agents/#mcp