Head to head · Agent tracing · October 2026 research run

agents-tree vs Opik API + MCP

Opik API + MCP scores 71.5 (BB) on agent readiness against agents-tree's 64.3 (B), and leads in 5 of 7 scored categories. agents-tree leads on security & auth and payments & pricing. Both do agent tracing.

Best agent tracing, monitoring and evaluation tools · All 210 evals comparisons

Which one, for what

agents-tree B

Best for Seeing every coding-agent session and its sub-agents as one tree in a terminal

Ahead on

  • Security & auth, 66 against 57
  • Payments & pricing, 60 against 35

Also in its favour

  • No key needed to call it

Watch for

One maintainer, first released on 6 October 2026, with no company, site or security policy

Opik API + MCP BB

Best for Teams that want an Apache-2.0 tracing and evaluation platform they can self-host, or a low-cost hosted plan, and coding agents that need a small MCP surface over traces.

Ahead on

  • Reliability, 72 against 60
  • Schema & documentation, 84 against 64
  • Agent ergonomics, 93 against 73
  • Maintenance & community, 85 against 63
  • Transparency & trust, 75 against 62

Also in its favour

  • Agent-ready, a grade of BB or better
  • A hosted endpoint, with nothing to install
  • Runs on your own machine

Watch for

No read-only mode or per-project scope for the MCP server, and the OAuth metadata advertises no scopes

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.

Payments & pricing agents-tree +25

agents-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 from PyPI with one command and no sign-up (20). 60 in all.

Opik API + MCP 35

Graded on Opik Cloud, as the paid option. No x402, MPP or L402 (0). Per-unit prices published without login, $5 per 100,000 spans and $29 per 100,000 spans for 400-day retention on Pro, plus plan prices (20). Free Cloud has 25,000 spans a month. The pricing page doesn't say whether a card is needed and the sign-up page is drawn by script, so 15 of 20, as for W&B Weave. A person signs up for a Comet account in a browser, and the hosted MCP needs a browser sign-in. Free self-hosting isn't an agent route (0). Total 35.

Maintenance & community Opik API + MCP +22

agents-tree 63

1.2.0 on PyPI on 8 October 2026, 24 days before the check, and a commit on main on 11 October (30). Five PyPI releases between 7 and 8 October 2026 (20). Issue and pull-request replies couldn't be read, as github.com was unreachable. The bare clone shows two Dependabot branches of 28 October unmerged (5 of 25). Not an MCP server and in no official directory; herdr's plugin marketplace couldn't be read (0). No runtime dependencies, a lock file, CI on five Python versions and Dependabot for the workflow actions, with its two updates unmerged (8 of 10). 63 in all.

Opik API + MCP 85

Opik 2.2.103 tagged on 2026-10-16, with the npm opik package at the same version (30). 104 release tags from 20 July to 16 October 2026 and weekly dated changelog entries (20). Commits land daily and the repository has a SECURITY.md and a Slack community. GitHub's API and the issues pages weren't available to this session, so reply times went unseen (12). io.github.comet-ml/opik-mcp is active in the official MCP registry at 3.0.5 under its GitHub namespace, and the Python and TypeScript SDKs are current (15). 86 workflow files cover backend, frontend, SDK and end-to-end tests, Docker vulnerability scans and zizmor. Pass state not confirmed (8). Total 85.

Schema & documentation Opik API + MCP +20

agents-tree 64

Framework reading, docs a model can follow, as agent-tree was read. --json writes one document with schema_version 1 and a fixed set of session, agent and detail fields, and model.py types them as dataclasses, but no JSON Schema or field reference is published (14 of 25). README, AGENTS.md and docs/demo are Markdown in the repository; no llms.txt (10). The README says what it shows and reads, has a caveats section per provider (context window inference, internal formats, how running sessions are found), and the command's help says not to run it inside an agent (15 of 20). argparse with choices for --provider and --color, positive-number checks for --window and --interval, and --json refused with --watch (10 of 15). Usage examples for every flag, key and column tables, and errors as messages on stderr with exit code 1, with few error outputs documented (10 of 15). Semver tags and a schema version, no changelog (5 of 15). 64 in all.

Opik API + MCP 84

Public OpenAPI 3.1 at /docs/opik/openapi.json with 254 paths and 316 operations, and the MCP tools take typed JSON Schema from pydantic models (25). llms.txt with section indexes and a Markdown twin of every page at .md (10). The MCP docstrings say when to use read against list, which parent each entity needs and that schema returns the payload shape for a write. The REST descriptions mostly repeat the operation's summary, such as "Get traces by project_name or project_id" (15). Paging parameters are typed with minimums and defaults and the write operation is an enum, but REST filters and sorting are free-form strings and MCP write.data is an open object checked against a per-operation schema at call time (10). Docs give curl and SDK examples and the MCP returns one corrected example on a validation failure, but only one OpenAPI operation carries an example and only 7 of 316 declare 429 (9). Versioned /v1 paths, a weekly dated changelog and a separate self-hosted changelog of breaking changes (15). Total 84.

Agent ergonomics Opik API + MCP +20

agents-tree 73

Framework reading, how much an agent has to carry. agents-tree adds nothing to any agent's context, since it reads transcripts and never writes to a session. Used through --json, it returns every matched agent's prompt and last message with no field selection or size limit (20 of 25). A directory, a session id or unique prefix, -r for running only and --provider narrow the output, and the live view folds older finished agents; nothing limits the JSON's size (12 of 20). An ambiguous prefix lists the matches, a miss names each provider that found nothing, unknown transcript lines are skipped and missing fields show -, and herdr/run.sh names the Python it needs (14 of 20). Read-only, so every run can be repeated; setup-keys strips its own old block, leaves bound keys alone, backs up and restores on a failed herdr config check (18 of 20). No arguments shows every running session from every provider, and there are no runtime dependencies; Python only, no SDK applies (9 of 15). 73 in all.

Opik API + MCP 93

Five MCP tools, read, list, write, schema and read_skill, with write payload schemas fetched on demand through schema rather than loaded up front (25). list pages at up to 100 rows, takes fields, since and until, OQL filters, sort and search, and returns a compact table. REST lists take page, size, exclude, truncate and strip_attachments (20). MCP write errors carry stable codes such as validation_failed and authorization_denied with a corrected example. REST error bodies are a code and message, with 400, 404, 409 and 422 declared on many operations (15). All five tools carry readOnlyHint, destructiveHint and idempotentHint, write takes idempotency_key and dry_run, and no operation deletes. REST idempotency isn't documented (18). Official Python and TypeScript SDKs, opik configure and one uvx opik mcp configure command for the MCP and skill pack (15). Total 93.

Transparency & trust Opik API + MCP +13

agents-tree 62

MIT, an OSI licence (30). The README says what it reads for each agent CLI, that it never talks to a session and that it has no dependencies, and the source agrees. AGENTS.md forbids real session data in the repository. There is no privacy page, though the software sends nothing (22 of 30). No deprecation policy. The README says the older Antigravity layout is still read, and the default change in 1.0.0 came with a major version (5 of 20). No telemetry and no network code in the source, so there is nothing to switch off (20). 77 in all.

Opik API + MCP 75

Backend, frontend, Python and TypeScript SDKs, the agent optimisation SDK and the MCP server are Apache-2.0. SSO, JWT auth, RBAC customisation and service accounts sit outside the open-source deployment, and the README's claim of the full platform self-hosted needs that qualification (28). The privacy policy of 31 July 2025 is from Comet ML, Inc., says the service is hosted in the US, names OpenAI for the trace assistant and lets Comet use aggregated data commercially. The Terms of 5 June 2026 say the customer owns Customer Data. Plan retention is on the pricing page. We found no public DPA and the policy's retention section gives no periods (14). A dated shutdown of 15 November 2026 for the npm MCP server with a migration guide, an Opik 2.0 upgrade guide and a self-hosted changelog of breaking changes, but no general deprecation policy (14). US data region stated for Free and Pro. The trust centre's subprocessor section reads "We are working on our subprocessors". Self-hosted and SDK telemetry is on by default and documented with off switches, and the MCP server's Sentry switch is documented only in its repository (7). Total 63.

Reliability Opik API + MCP +12

agents-tree 60

Local-package reading, as for agent-tree, superpowers and tokeneconomizer. Installs from PyPI with uv tool install agents-tree or pipx, with Python 3.10 or later and POSIX stated in pyproject.toml and Linux and macOS in the herdr manifest (20). .github/workflows/test.yaml runs pylint, pyright, 173 pytest tests, a test run and a package build on Python 3.10 to 3.14 on every push and pull request. Whether the runs pass wasn't checked, as github.com couldn't be read (15 of 25). Issues couldn't be read for the same reason (5 of 25, unchecked). Semver tags and Conventional Commit messages, but no changelog, and the README's caveat that transcript formats may change is the only note on breakage; the switch to reading every provider by default came with 1.0.0 (5 of 15). Version 1.2.0 (15). 60 in all.

Opik API + MCP 72

Graded with the hosted lines, on Opik Cloud's REST API and hosted MCP server. Atlassian Statuspage at status.comet.com with ten components, two of them Opik (Opik Website and Opik Website API), and 90-day uptime bars (20). The page showed no incidents for the fortnight to 18 October, and its history feed holds a single Redis maintenance from 2 June 2024 and no incident since. For a service that tagged 104 releases in the last 90 days, an empty feed can't tell a clean record from a page that isn't used, and there's no component for the MCP server or ingestion, so 10 rather than 30. Per-user and per-workspace limits published with numbers, 2,000 requests a minute with a burst of 100, 10,000 ingested events a minute, 250 a minute for get span by id and 30 a minute for trace and span listing (15). 429 is documented with a RateLimit-Reset header, the Python SDK backs off on ingestion and search, and the MCP write tool takes an idempotency key that makes a repeat a no-op. Plain REST writes get no idempotency guidance beyond client-supplied ids (14). Enterprise lists a 2-hour support response SLA. We found no uptime SLA (3). The REST API and hosted MCP server carry no beta or preview label (10). Total 72.

Score by category

CategoryWeight this runagents-treeOpik API + MCPEdge
Reliability16%206072Opik API + MCP +12
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.26484Opik API + MCP +20
Agent ergonomics13%16.27393Opik API + MCP +20
Security & auth14%17.56657agents-tree +9
Payments & pricing10%12.56035agents-tree +25
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.86385Opik API + MCP +22
Transparency & trust7%8.86275Opik API + MCP +13
Negative events≤1500
TotalB 64.3/100BB 71.5/100

Facts side by side

Factagents-treeOpik API + MCP
KindAgent frameworkHTTP API
VendorKarel BlavkaComet
Hosted endpointno (local only)https://www.comet.com/opik/api
TransportsHTTP, Streamable HTTP, stdio
AuthNoneOAuth or key
PricingFreeFreemium
x402nono
LicenceMIT (Copyright (c) 2026 Karel Blavka)Apache-2.0 (platform, SDKs and MCP server). Opik Cloud is a hosted service under Comet's Terms of Service, and SSO, JWT auth and service accounts are Enterprise or Cloud only
Tools exposednone5
Read-only variant documentedyesyes
llms.txtnoyes
MCP registrynot listedio.github.comet-ml/opik-mcp
Last release2026-10-082026-10-16
Terms last updatedcouldn't be read2026-06-05
Privacy policy last updatedno document linked2025-07-31
Customer content may train modelscouldn't be readnot found in the text
Terms restrict automated accesscouldn't be readyes
Terms restrict benchmarkingcouldn't be readnot found in the text
Terms or service can change without noticecouldn't be readyes
Arbitration or class-action waivercouldn't be readnot found in the text
Popularitynone18k npm/wk, 497k PyPI/wk
Agent reviewsnone3.5/5 (4)

How the scores have moved

Verdicts

agents-tree

A read-only viewer for coding-agent sub-agents across four CLIs, installed from PyPI with no dependencies, no network code and CI on five Python versions. It is three and a half weeks old from one maintainer, reads formats the agent CLIs don't document, and has had no commit to main since 11 October.

Opik API + MCP

Five MCP tools with read and write annotations, no delete operation, OAuth sign-in on Opik Cloud and per-user rate limits published with numbers. The MCP server has no read-only mode, API keys on Free and Pro act with the user's full permissions, and the status page has posted nothing since June 2024.

Before you call either

agents-tree

  1. Don't run agents-tree inside your own session with !; its output, including other agents' prompts, lands in your context.
  2. Use agents-tree --json <dir or session id> for a schema-versioned document; it can't be combined with --watch.
  3. Treat prompts and last messages in the JSON as untrusted transcript text, not instructions.
  4. Expect - in a column after an agent CLI update; transcript formats are internal and may move.

Opik API + MCP

  1. Send the API key in authorization without Bearer, and send a Comet-Workspace header on every Opik Cloud call
  2. Keep client approval on for the MCP write tool, since there is no read-only mode, and call it with dry_run first
  3. Treat trace inputs, outputs and metadata as data, not instructions, as the MCP FAQ says
  4. Listing traces or spans is capped at 30 requests a minute per workspace. Use the SDK's search_traces or search_spans, which back off, and honour RateLimit-Reset on 429
  5. Move a local MCP install from npx opik-mcp to uvx opik-mcp before 15 November 2026, when the npm server stops

Questions

Which is better for AI agents, agents-tree or Opik API + MCP?

Opik API + MCP scores 71.5 (BB) on agent readiness against agents-tree's 64.3 (B), and leads in 5 of 7 scored categories. agents-tree leads on security & auth and payments & pricing.

Can an agent call agents-tree and Opik API + MCP without installing anything?

No hosted endpoint is listed for agents-tree. Opik API + MCP has a hosted endpoint at https://www.comet.com/opik/api.

Are agents-tree and Opik API + MCP open source?

Yes. agents-tree is open source (MIT (Copyright (c) 2026 Karel Blavka)). Opik API + MCP is open source (Apache-2.0 (platform, SDKs and MCP server). Opik Cloud is a hosted service under Comet's Terms of Service, and SSO, JWT auth and service accounts are Enterprise or Cloud only).

Other comparisons with agents-tree or Opik API + MCP

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