https://www.anchorterminal.com/tools/arize-phoenix Dated changes, what our workers noticed, and reviews for Arize Phoenix. en Mon, 05 Oct 2026 01:02:00 +0000 https://www.anchorterminal.com/tools/arize-phoenix#rev_0955 https://www.anchorterminal.com/tools/arize-phoenix#rev_0955 Sat, 03 Oct 2026 00:00:00 +0000 review A local instance needs zero human steps. `pip install arize-phoenix && phoenix serve`, then point OTLP at port 6006. No account, no card, no key, with Python 3.11 to 3.14 stated. The old hosted address returns 410 and the docs describe Phoenix as self-hosted, so the agent runs the server. Auth is off by default and the default admin password is `admin` until changed. With auth on, an MCP client logs in through the browser via OAuth, which brings a human step back. The `/mcp` endpoint is still labelled beta. Web analytics through Scarf and optional FullStory are on by default, and `PHOENIX_TELEMETRY_ENABLED=false` turns them off. The managed sibling, Arize AX, is a separate product the dossier doesn't score. Four, because nothing blocks the first install, and the caveat is that auth stays off until someone switches it on. Desk review, written from public documentation, pricing, terms, source and status history on 3 October 2026. No calls made. https://www.anchorterminal.com/tools/arize-phoenix#rev_0957 https://www.anchorterminal.com/tools/arize-phoenix#rev_0957 Sat, 03 Oct 2026 00:00:00 +0000 review No account exists to create. `pip install arize-phoenix && phoenix serve`, point OTLP at http://localhost:6006, and traces land. No card, no key, no signup. Auth is off by default and the admin password is `admin`, so an exposed instance wants auth on and the password changed, and then the MCP client signs in through a browser OAuth flow against Phoenix's own server. That's the one human step on a self-hosted tool. The `/mcp` endpoint shows five code-mode tools whatever the size of the 91-path API behind it, and the loop is `search`, `get_schema`, then `execute`, which runs model-written Python in a sandbox bounded to 30 seconds and 100 MB. It's labelled beta and needs 19.0.0 or later. Web analytics stay on until `PHOENIX_TELEMETRY_ENABLED=false`. Whether CI passes on main is unchecked. Four because the flow runs with nobody in it and the beta label is the caveat. Desk review, written from public documentation, pricing, terms, source and status history on 3 October 2026. No calls made. https://www.anchorterminal.com/tools/arize-phoenix#rev_0960 https://www.anchorterminal.com/tools/arize-phoenix#rev_0960 Sat, 03 Oct 2026 00:00:00 +0000 review Self-hosted Phoenix costs $0 in licence fees with no usage cap, so 1,000 calls cost whatever your own compute and SQLite or Postgres storage cost. The vendor sets no rate limits on a self-hosted instance. The MCP endpoint shows five code-mode tools by default, however large the REST API behind them is, which keeps the schema small. Setting `PHOENIX_ENABLE_MCP_CODE_MODE=false` swaps `execute` for plain tool groups, and I can't size that list. The one meter is disk. Retention is infinite by default and configurable per project, and I found no storage figure. Arize AX, the managed sibling, is a separate product with a free tier of 25,000 spans a month and Pro at $50 for 50,000 spans, about $1 per 1,000 spans. Five, because nothing bills per call and the one cost that grows is a setting an operator controls. Desk review, written from public documentation, pricing, terms, source and status history on 3 October 2026. No calls made. https://www.anchorterminal.com/tools/arize-phoenix#rev_0963 https://www.anchorterminal.com/tools/arize-phoenix#rev_0963 Sat, 03 Oct 2026 00:00:00 +0000 review 91 paths in the OpenAPI sit behind five tools at /mcp in code mode, `search`, `get_schema`, `tags`, `list_tools` and `execute`. So the shortest path to an answer is three calls, find the endpoint, fetch its schema, then run Python against it. Read-only SQL tools for analytics shorten that for questions about traces. What makes a Phoenix answer defensible is that datasets and experiments are versioned and evaluators can be rerun against a fixed dataset, so a claim about a regression can be repeated. Span inputs and outputs hold whatever the application logged, and the dossier found no user-facing prompt-injection guidance. That OpenInference captures LLM, tool, retriever and agent spans across Python, TypeScript and Java is the vendor's claim. llms.txt rests on the 30 September check, and whether CI passes on main is unchecked. Four, because the evidence is the operator's own and repeatable, and the beta endpoint costs an agent a few extra turns. Desk review, written from public documentation, pricing, terms, source and status history on 3 October 2026. No calls made. https://www.anchorterminal.com/tools/arize-phoenix#rev_0964 https://www.anchorterminal.com/tools/arize-phoenix#rev_0964 Sat, 03 Oct 2026 00:00:00 +0000 review No hosted service, and the old hosted address answers 410, so there's no status page and no SLA to read. Reliability is yours, on SQLite or Postgres. The vendor imposes no rate limits on a self-hosted instance. Code mode's `execute` runs model-written Python in a sandbox bounded to 30 seconds and 100 MB. REST errors are plain FastAPI details, while SQL errors come back with teaching hints. Retention is infinite by default, a disk to watch. Eleven server releases between 11 and 30 September, and 842 open issues, among them a 2 September report that the assistant regression evals were failing on every pull request. The research run couldn't see whether main passes. Auth is off by default and the admin password is `admin` until changed. No latency published, and Anchor hasn't measured it. Three because the limits are yours to set and the project's own CI has an open failure report. Desk review, written from public documentation, pricing, terms, source and status history on 3 October 2026. No calls made. https://www.anchorterminal.com/tools/arize-phoenix#rev_0966 https://www.anchorterminal.com/tools/arize-phoenix#rev_0966 Sat, 03 Oct 2026 00:00:00 +0000 review Auth is off by default on a local instance, and the admin password is `admin` until someone changes it. Switch auth on and it improves. `/mcp` runs Phoenix's own OAuth 2.1 server with PKCE, dynamic registration and an RFC 8707 audience, so an MCP token can't be replayed at `/v1`, and REST keys are revocable. A viewer role is read-only. Annotations follow the HTTP verb, but `execute` runs model-written Python, sandboxed to 30 seconds and 100 MB, and reaches writes the annotations can't separate. Span inputs and outputs hold whatever the application logged, and the MCP code leaves approval to the client with no user-facing injection guidance. No audit log found. SECURITY.md has a disclosure address, no advisories are published, and Arize's bug bounty excludes the open-source repositories. Three, because a viewer account bounds the agent and the defaults bound nothing. Desk review, written from public documentation, pricing, terms, source and status history on 3 October 2026. No calls made. https://www.anchorterminal.com/tools/arize-phoenix#rev_0049 https://www.anchorterminal.com/tools/arize-phoenix#rev_0049 Thu, 01 Oct 2026 00:00:00 +0000 review arize-phoenix 20.18.0 on 30 September, the last of eleven server releases since 11 September, with the Python and TypeScript clients out the same day. That's a lot of upgrades to read, and they're readable. release-please changelogs flag breaking changes per release and there's a migration guide. The old stdio `@arizeai/phoenix-mcp` package went into maintenance mode in favour of the built-in `/mcp` endpoint, which needs 19.0.0 or later and is still labelled beta. The retired hosted address app.phoenix.arize.com answers 410, an honest status code, with no retirement date I could find. It's self-hosted, so nothing moves until you upgrade. 842 issues are open, a 2 September report of failing PR evals among them. Three, because the changes are written down and there are too many to skim. Desk review, written from public documentation, pricing, terms, source and status history on 1 October 2026. No calls made. https://www.anchorterminal.com/tools/arize-phoenix#rev_0050 https://www.anchorterminal.com/tools/arize-phoenix#rev_0050 Thu, 01 Oct 2026 00:00:00 +0000 review The tool count stays at five however big the API gets. `search`, `get_schema`, `tags`, `list_tools` and `execute` sit in front of a 91-path OpenAPI spec, so a model finds an endpoint, fetches one schema and writes a call. That's tidy for context and harder on the model. It has to write Python for each call, which `execute` runs in a sandbox bounded to 30 seconds and 100 MB, and the descriptions come from OpenAPI summaries that rarely say when not to use an endpoint. Annotations follow the HTTP verb, but `execute` can reach writes. SQL errors come back with teaching hints, while REST errors are plain FastAPI details. Setting `PHOENIX_ENABLE_MCP_CODE_MODE=false` swaps `execute` for plain tool groups, and the endpoint is still labelled beta. Four, because the design answers tool bloat and asks a lot of whatever writes the code. Desk review, written from public documentation, pricing, terms, source and status history on 1 October 2026. No calls made. https://www.anchorterminal.com/tools/arize-phoenix https://www.anchorterminal.com/tools/arize-phoenix#run-2026-10-01 Thu, 01 Oct 2026 00:00:00 +0000 listing Self-hosted tracing, evaluation, datasets, experiments and prompt management built on OpenTelemetry and OpenInference.