Opik MCP Server

**The official Model Context Protocol (MCP) server for Opik, the open-source LLM observability and evaluation platform, built by Comet.**

Plug your AI host (Claude Code, Cursor, VS Code Copilot, MCP Inspector) directly

into your Opik workspace: read traces, log scores, save prompt versions, and ask

Ollie, Opik's in-product AI assistant, investigative questions, all

from the chat.

Built for LLM engineers who already run Opik and want to drive it from the same

AI assistant they code with.

**Migrating from the old npx opik-mcp?** The TypeScript server is deprecated
and sunsets on 2026-11-15. Swap npx -y opik-mcp for **uvx opik-mcp@latest**
in your MCP client config. Full guide: [legacy/typescript/MIGRATION.md](./legacy/typescript/MIGRATION.md).

code

You:    "Why did the experiment 'gpt-4o-rerank-v3' regress on factuality?"
Claude: → ask_ollie → reads experiment + traces → "Three traces failed because…"

You:    "Score trace 7f2e… 0.9 on helpfulness with reason 'great recovery'."
Claude: → write(score.create) → done

---

Install

opik-mcp is a Python package (requires Python 3.13+). The recommended way to

run it is uvx, which fetches and runs the latest published version on demand —

no global install, no virtualenv juggling.

Install [uv](https://docs.astral.sh/uv/) once:

bash

curl -LsSf https://astral.sh/uv/install.sh | sh   # macOS / Linux
# or: brew install uv

You'll need two things from your Opik workspace:

**OPIK_API_KEY** — get it from [comet.com/api/my/settings/](https://www.comet.com/api/my/settings/).
**OPIK_WORKSPACE** — your workspace name (lowercase, as it appears in the URL). E.g. https://www.comet.com/acme-ai/... → OPIK_WORKSPACE=acme-ai. Optional — defaults to default (the Opik SDK convention), which is correct for local/OSS installs; cloud users with a named workspace should set it. COMET_WORKSPACE is accepted as a deprecated alias.

Pre-release note: opik-mcp (Python) is not yet published to PyPI. Until
the first PyPI release lands, replace uvx opik-mcp in any snippet below with:
uvx --from git+https://github.com/comet-ml/opik-mcp.git opik-mcp

**OPIK_WORKSPACE is optional.** Omit the OPIK_WORKSPACE line/key in any
snippet below and the server uses the default workspace (correct for
local/OSS installs). Set it only if you connect to a named cloud workspace.

Claude Code

Add the server with one command:

bash

claude mcp add --transport stdio opik-mcp \
  --env OPIK_API_KEY= \
  --env OPIK_WORKSPACE= \
  -- uvx opik-mcp

Or edit ~/.claude.json directly:

json

{
  "mcpServers": {
    "opik-mcp": {
      "type": "stdio",
      "command": "uvx",
      "args": ["opik-mcp"],
      "env": {
        "OPIK_API_KEY": "",
        "OPIK_WORKSPACE": ""
      }
    }
  }
}

Restart Claude Code. Verify with /mcp — opik-mcp should appear as connected.

Then, in the chat, ask: "list my Opik projects" — Claude will call the list

tool and you'll see your workspace's projects.

Cursor

Edit ~/.cursor/mcp.json (global) or .cursor/mcp.json (project), or open

Cmd+Shift+J → Features → Model Context Protocol:

json

{
  "mcpServers": {
    "opik-mcp": {
      "type": "stdio",
      "command": "uvx",
      "args": ["opik-mcp"],
      "env": {
        "OPIK_API_KEY": "",
        "OPIK_WORKSPACE": ""
      }
    }
  }
}

Reload Cursor; the green dot next to opik-mcp in the MCP panel confirms the

connection. Ask in chat: "list my Opik projects".

Cursor 60s timeout. Cursor enforces a hard tool-call timeout that doesn't
reset on progress notifications. Long ask_ollie turns will fail on Cursor.
See Known host limits.

VS Code Copilot

.vscode/mcp.json in your workspace (or User Settings JSON):

json

{
  "servers": {
    "opik-mcp": {
      "type": "stdio",
      "command": "uvx",
      "args": ["opik-mcp"],
      "env": {
        "OPIK_API_KEY": "",
        "OPIK_WORKSPACE": ""
      }
    }
  }
}

Reload the window; the Copilot Chat MCP indicator shows opik-mcp once

the server is reachable. Ask in chat: "list my Opik projects".

MCP Inspector (manual testing)

bash

OPIK_API_KEY= OPIK_WORKSPACE= \
  npx @modelcontextprotocol/inspector uvx opik-mcp

Self-hosted Opik

Add COMET_URL_OVERRIDE (and OPIK_URL if Opik lives at a non-default path) to

the same env block in your host config:

json

{
  "mcpServers": {
    "opik-mcp": {
      "type": "stdio",
      "command": "uvx",
      "args": ["opik-mcp"],
      "env": {
        "OPIK_API_KEY": "",
        "COMET_URL_OVERRIDE": "https://opik.your-company.com",
        "OPIK_MCP_ANALYTICS_SOURCE": ""
      }
    }
  }
}

ask_ollie and run_experiment are available on Comet Cloud only — on

self-hosted those calls will fail at dispatch, so use read / list / write

directly. Setting OPIK_MCP_ANALYTICS_SOURCE="" opts your install out of the

cloud-Comet source label on telemetry events.

---

Tools

opik-mcp exposes a small, outcome-oriented surface — six tools that cover

the full lifecycle (read → annotate → curate → author → iterate).

Tool	Purpose
[`read`](#read)	Universal read by id / name / `opik://` URI
[`list`](#list)	Universal list with optional name filter + pagination
[`ask_ollie`](#ask_ollie)	Investigate / synthesize via the Opik in-product assistant
[`write`](#write)	Universal write — log traces/spans, score, comment, save prompts, manage test suites & experiments
[`schema`](#schema)	Introspect write-operation schemas (used by the LLM to construct valid payloads)
[`run_experiment`](#run_experiment)	Run an evaluation experiment end-to-end via Ollie

`read`

One tool for any "show me X" question. Takes an entity_type plus an id

(UUID or, for nameable types, a name) or a full opik:// URI. Composite reads

(trace, prompt) inline their children so a single call returns the full

picture.

Supported entities: project, trace, span, test_suite, experiment,

prompt. Name-based lookup is available for project, experiment, prompt,

test_suite (slower — two API calls — and may return multiple matches).

python

read(entity_type="trace", id="7f2e3c8a-…")
read(entity_type="project", id="demo")          # name lookup
read(entity_type="trace", id="opik://traces/7f2e3c8a-…")

`list`

Browse a collection with optional name filter and pagination. Project-scoped

types (trace, test_suite_item, prompt_version) require their parent UUID.

python

list(entity_type="experiment", page=1, size=25)
list(entity_type="experiment", name="rerank")          # name substring filter
list(entity_type="trace", project_id="") # traces of one project

`ask_ollie`

For investigative questions, cross-entity synthesis, or anything that needs

Opik domain expertise. Ollie has direct read access to your workspace and can

execute writes (scores, comments, test-suite items, prompt versions) mid-stream

when asked.

python

ask_ollie(query="Why are spans in project 'demo' slower this week than last?")
ask_ollie(query="Compare experiments A and B on factuality. Score the bottom 5 traces of A 0.2 with reason.")

Returns the assistant's final text plus a thread_id. Pass it back on

follow-ups to preserve context — Ollie has no memory across threads.

YOLO mode (default). Writes Ollie performs mid-stream execute without a

per-action confirmation. Each auto-approval is logged as a JSON audit row on

the opik_mcp.audit Python logger. To require confirmation instead, set

OPIK_MCP_AUTO_APPROVE=disabled — Ollie's confirm requests then surface as

typed errors you can manually re-issue.

Available on Comet Cloud only.

`write`

Universal write dispatcher. Pass operation + data and the dispatcher

validates the payload, applies the right REST verb, and returns the

backend response.

Operations:

Operation	What it does
`trace.create`	Log a single trace (or a batch). Parent for spans / scores / comments.
`trace.update`	Finalize or amend an existing trace.
`span.create`	Log a span on an existing trace (or a batch).
`score.create`	Attach a numeric feedback score to a trace, span, or thread.
`comment.create`	Attach a free-text comment to a trace, span, or thread.
`prompt_version.save`	Save a new prompt version (creates the prompt by name if missing).
`test_suite.create`	Create an evaluation test suite.
`test_suite_item.upsert`	Upsert items into a test suite (always the envelope shape).
`experiment.create`	Create an experiment scoped to a test suite.
`experiment_item.create`	Attach trace + dataset_item rows to an experiment.

python

write(operation="score.create", data={
  "target": "trace",
  "target_id": "7f2e3c8a-…",
  "name": "helpfulness",
  "value": 0.9,
  "reason": "great recovery"
})

`schema`

Inspect the exact JSON shape and required fields of any write operation before

you call it — useful when you're not sure what data should look like. Returns

the schema, OAuth scope, and one validated example. Pure lookup, no backend

call.

python

schema(operation="score.create")
schema(operation="prompt_version.save")

`run_experiment`

Run an evaluation experiment end-to-end via Ollie. Takes a single

experiment_config dict that mirrors Opik's experiment shape (prompt, test

suite, scorers); Ollie executes the run and writes results back as an Opik

experiment.

python

run_experiment(experiment_config={
  "test_suite_name": "qa-eval-v2",
  "prompt_name": "welcome-msg",
  # … see `schema(operation="experiment.create")` for the full shape
})

Available on Comet Cloud only.

---

Configuration

Every setting is an environment variable. Required ones in bold.

Identity / endpoint

Variable	Default	Notes
`OPIK_API_KEY`	—	Required for `ask_ollie` and any authenticated read/write.
`OPIK_WORKSPACE`	`default`	Workspace name. Optional — falls back to `default` (Opik SDK convention). Cloud users with a named workspace should set it.
`COMET_WORKSPACE`	—	Deprecated alias for `OPIK_WORKSPACE` (backward compat). `OPIK_WORKSPACE` wins if both are set.
`COMET_WORKSPACE_ID`	—	Optional workspace UUID. Stamped into analytics events when set so BI can join on a stable id rather than the (mutable) workspace name.
`COMET_URL_OVERRIDE`	`https://www.comet.com`	Set to your self-hosted Comet host, or `https://dev.comet.com` for staging.
`OPIK_URL`	derived from `COMET_URL_OVERRIDE` + `/opik/api`	Override only if Opik lives on a different host/path than the Comet UI.
`OPIK_DEFAULT_PROJECT_NAME`	_unset_	When set, the per-session `instructions` blob tells the LLM to pass this as `project_name` on every tool call unless the user names a different project.

Server / transport

Variable	Default	Notes
`OPIK_MCP_TRANSPORT`	`stdio`	`stdio` for host-launched, `streamable-http` to listen on a port.
`OPIK_MCP_HOST`	`127.0.0.1`	uvicorn bind host (`streamable-http` only).
`OPIK_MCP_PORT`	`8080`	uvicorn bind port (`streamable-http` only).
`OPIK_MCP_RELOAD`	`false`	`true` to enable uvicorn `--reload` (dev only).
`OPIK_MCP_AS_URL`	_unset_	OAuth Authorization Server URL, advertised in `/.well-known/oauth-protected-resource` (RFC 9728) and used as the proxy target for AS-discovery probes. Required for MCP hosts to bootstrap the OAuth dance over HTTP.
`OPIK_MCP_RESOURCE_URI`	_unset_	Canonical public URI of this server, advertised as `resource` in the protected-resource metadata and used to derive the `WWW-Authenticate` hint.
`OPIK_MCP_LOG_LEVEL`	`INFO`	stderr logger threshold.

Choosing a transport

opik-mcp performs no local credential validation on HTTP transport: any

well-formed Authorization: Bearer … (an Opik API key or an opik_mcp_at_…

OAuth access token) is forwarded verbatim to opik-backend, which is the

single point of auth enforcement. Pick the transport by deployment shape:

Scenario	Transport
MCP client and Opik on the same machine (local OSS install)	stdio (recommended — simplest, no port, no OAuth setup)
Local MCP client → remote Opik (Comet cloud / self-hosted)	stdio with `OPIK_API_KEY`, or HTTP with OAuth (`OPIK_MCP_AS_URL` pointing at the backend)
Hosted opik-mcp behind the same edge as opik-backend	HTTP — bearers are validated by the backend per request

Note for local OSS installs: the OSS backend does not authenticate requests,

so an HTTP opik-mcp in front of it is as open as the OSS REST API itself.

Keep the default 127.0.0.1 bind (and prefer stdio) on shared networks.

Ollie / long calls

Variable	Default	Notes
`OPIK_MCP_AUTO_APPROVE`	`enabled`	`disabled` to require a per-action approval before Ollie's mid-stream writes proceed. On hosts that advertise the MCP `elicitation` capability the user sees a yes/no prompt; on dumber hosts the request surfaces as a typed error you can manually re-issue.
`OPIK_MCP_ELICIT_TIMEOUT_SECONDS`	`60`	How long Ollie's mid-stream confirmation prompt may wait for the user before being treated as a cancel. `0` disables the bound (debug only).
`OPIK_MCP_POD_READY_TIMEOUT_S`	`120`	Ollie pod cold-start poll cap.
`OPIK_MCP_POD_READY_INTERVAL_S`	`2`	Cold-start poll interval.
`OPIK_MCP_HEARTBEAT_INTERVAL_S`	`15.0`	Watchdog cadence — emits a `notifications/progress` tick when the pod is silent, keeping host timeouts at bay.
`OPIK_MCP_STREAM_IDLE_TIMEOUT_S`	`300.0`	Hard ceiling on pod silence before `ask_ollie` aborts. `0` disables (debug only).

Telemetry

Anonymous usage events (event type + timing only — no query content). A SHA-256

digest of your API key is included so support can find your account; the raw

key never leaves the process. Opt out: OPIK_MCP_ANALYTICS_ENABLED=false.

Variable	Default	Notes
`OPIK_MCP_ANALYTICS_ENABLED`	`true`	Set to `false` to disable all telemetry.
`OPIK_MCP_ANALYTICS_URL`	`https://stats.comet.com/notify/event/`	Override for staging.
`OPIK_MCP_ANALYTICS_ENVIRONMENT`	`prod`	Tag on every event (`prod` / `staging` / `dev`).
`OPIK_MCP_ANALYTICS_SOURCE`	`comet.com`	Receiver uses this to mark `on_prem=False`. On-prem installs should override to `""` or their own domain.
`OPIK_MCP_ANALYTICS_CONNECT_TIMEOUT_S`	`5.0`	HTTP connect timeout.
`OPIK_MCP_ANALYTICS_TOTAL_TIMEOUT_S`	`10.0`	HTTP total request timeout.

---

Known host limits

The MCP spec lets hosts reset their tool-call timeout on

notifications/progress — opik-mcp emits one per Ollie SSE event plus a

15-second watchdog heartbeat. Reality is uneven:

Claude Code — no documented tool-call timeout; heartbeat keeps the call

alive until message_end. Recommended.

Cursor — hard 60s timeout that does not reset on progress

(upstream bug).

Long Ollie turns will fail. Keep ask_ollie queries focused.

MCP Inspector — MAX_TOTAL_TIMEOUT bounds total duration (default 60s).

Raise it in the Inspector UI for long operations.

If a call gets stuck, set OPIK_MCP_LOG_LEVEL=DEBUG — heartbeat failures

(usually host disconnects) are logged on opik_mcp.ask_ollie at debug level.

---

Troubleshooting

**OPIK_API_KEY is required to use ask_ollie** — the var isn't reaching the

server process. In Claude Code / Cursor / VS Code, env vars only apply when

inside the env block of the MCP server config, not your shell. Restart the

host after editing.

**ask_ollie returns "pod not ready" after 2 minutes** — the Ollie pod

cold-start exceeded OPIK_MCP_POD_READY_TIMEOUT_S. Retry — the second call

usually hits a warm pod.

**ask_ollie / run_experiment fails with a dispatch error on self-hosted

Opik** — those tools are available on Comet Cloud only. Use read / list /

write directly on self-hosted.

Cursor call times out at 60s — Cursor's known bug, not opik-mcp. Either

shorten the Ollie query, or run the same operation on Claude Code which has no

hard cap.

---

Development

bash

git clone git@github.com:comet-ml/opik-mcp.git
cd opik-mcp
make install        # uv sync --extra dev
make check          # lint + typecheck + test
make run-dev        # uvicorn with --reload + DEBUG logs
make inspect        # MCP Inspector against the running server

Common targets:

Target	What it does
`make install`	`uv sync --extra dev`
`make run`	Run the MCP server (stdio by default).
`make run-dev`	Run with DEBUG logging + uvicorn `--reload`.
`make dev`	Run via `mcp dev` (Inspector dev-mode wrapper).
`make inspect`	Launch MCP Inspector against a running server.
`make test`	`uv run pytest -q`.
`make test-live`	Live end-to-end against `dev.comet.com` (set `OPIK_API_KEY` + `OPIK_WORKSPACE`).
`make lint`	`ruff check` + format check.
`make format`	`ruff format` + `ruff check --fix`.
`make typecheck`	`mypy`.
`make check`	`lint + typecheck + test`.

Repo layout:

code

opik-mcp/
├── src/opik_mcp/        ← server, tools, ask_ollie, analytics
├── tests/               ← pytest suites
├── scripts/             ← live-BE smoke + MCP-session smoke
├── legacy/typescript/   ← deprecated v2 TS server
├── pyproject.toml
└── Makefile

---

Get help

Open an issue for bugs and feature requests
Opik docs for SDK / backend documentation
Comet community Slack for questions

---

Upgrading from v2? The legacy TypeScript server still ships on npm as
opik-mcp@^2 (npx -y opik-mcp); source is preserved under
[legacy/typescript/](./legacy/typescript/). See
[legacy/typescript/DEPRECATED.md](./legacy/typescript/DEPRECATED.md) for
the support policy.

---

License

Apache-2.0.

Opik Mcp

Documentation

Opik MCP Server

Install

Claude Code

Cursor

VS Code Copilot

MCP Inspector (manual testing)

Self-hosted Opik

Tools

read

list

ask_ollie

write

schema

run_experiment

Configuration

Identity / endpoint

Server / transport

Choosing a transport

Ollie / long calls

Telemetry

Known host limits

Troubleshooting

Development

Get help

License

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`read`

`list`

`ask_ollie`

`write`

`schema`

`run_experiment`