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, Codex, opencode, or any MCP client) directly into your Opik workspace: read traces, log scores, and save prompt versions, 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.

You:    "Which traces in project 'demo' failed today?"
Claude: → list(entity_type="trace", project_name="demo") → "Three traces failed…"

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

Quick start

One command registers the server with the AI clients on your machine, installs the Opik skill pack, and verifies the connection. It needs uv and no Opik SDK:

uvx opik mcp configure

It detects Claude Code, Cursor, VS Code Copilot, Codex and opencode, and uses the hosted server on Opik Cloud (browser sign-in, no API key stored) or this local server elsewhere. Any other MCP client can take the hosted URL directly:

npx add-mcp https://www.comet.com/opik/api/v1/mcp --name opik-mcp

Setup guide, troubleshooting and FAQ: comet.com/docs/opik/mcp-server. The rest of this README covers the local server, which the command above sets up for self-hosted and open-source Opik, and which you can also configure by hand.

Manual 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 once:

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/.
• OPIK_WORKSPACE — your workspace name (lowercase, as it appears in the URL). E.g. https://www.comet.com/acme-ai/... → OPIK_WORKSPACE=acme-ai. COMET_WORKSPACE is accepted as a deprecated alias.

Cloud, with an API key: set it unless your account default is the one you want. Left out, the server sends default, which Comet resolves to your account's default workspace. That works, but if you actually work in a named workspace you will be pointed at a different one with nothing to tell you — your reads come back from the wrong place rather than failing.

Cloud, over OAuth: leave it unset. The workspace comes from the token you authorized, and the server ignores this setting entirely.

Local / open source: leave it unset. Open source Opik has a single workspace named default and no way to create others, which is exactly what the fallback gives you.

Self-hosted Comet: set it. Unlike open source, these deployments have real named workspaces, and the same silent-wrong-workspace risk applies.

Whichever applies, make sure the value is actually substituted. Snippets in the wild ship placeholders like <your-workspace> or ${input:OPIK_WORKSPACE}; pasted as-is, those are not workspace names. The server now refuses them outright rather than letting the backend answer with an auth error that explains nothing.

Claude Code

Add the server with one command:

claude mcp add --transport stdio opik-mcp \
  --env OPIK_API_KEY=<your-key> \
  --env OPIK_WORKSPACE=<your-workspace> \
  -- uvx opik-mcp

Or edit ~/.claude.json directly:

{
  "mcpServers": {
    "opik-mcp": {
      "type": "stdio",
      "command": "uvx",
      "args": ["opik-mcp"],
      "env": {
        "OPIK_API_KEY": "<your-key>",
        "OPIK_WORKSPACE": "<your-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:

{
  "mcpServers": {
    "opik-mcp": {
      "type": "stdio",
      "command": "uvx",
      "args": ["opik-mcp"],
      "env": {
        "OPIK_API_KEY": "<your-key>",
        "OPIK_WORKSPACE": "<your-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. See Known host limits.

VS Code Copilot

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

{
  "servers": {
    "opik-mcp": {
      "type": "stdio",
      "command": "uvx",
      "args": ["opik-mcp"],
      "env": {
        "OPIK_API_KEY": "<your-key>",
        "OPIK_WORKSPACE": "<your-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)

OPIK_API_KEY=<your-key> OPIK_WORKSPACE=<your-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:

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

Omit OPIK_WORKSPACE on an open-source deployment, where default is the only workspace; keep it on a self-hosted Comet, which has real named ones.

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

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, thread, agent_insights_issue) inline their children so a single call returns the full picture.

The record you name comes back whole. Inlined children do not: their bodies are fetched with the backend's truncate=true, so a field over ~10 KB is cut in ClickHouse and base64 images are replaced with "[image]" — one attachment echoed across 200 spans would otherwise cost more than everything else in the read. The answer says so in spanBodies / messageBodies, and any child is whole again through its own read("span", id) or read("trace", trace_id), which hit endpoints that have no truncate parameter at all.

An inlined collection is also bounded in length: 200 spans, 200 turns, 100 prompt versions. Past that, spansTruncated / messagesTruncated / versionsTruncated is true and a moreSpans / moreMessages / moreVersions line beside it carries the count and the exact list(...) call that continues from where the inlined part stopped.

Supported entities: project, trace, span, test_suite, experiment, prompt, thread, agent_insights_issue. Name-based lookup is available for project, experiment, prompt, test_suite (slower — two API calls — and may return multiple matches). thread and agent_insights_issue are project-scoped: pass project_id or project_name, or a link/URI that carries the project.

read(entity_type="trace", id="7f2e3c8a-…")
read(entity_type="project", id="demo")          # name lookup
read(entity_type="trace", id="opik://traces/7f2e3c8a-…")
read(entity_type="agent_insights_issue", id="<issue-uuid>", project_id="<project-uuid>")
read(entity_type="agent_insights_issue", id="https://www.comet.com/opik/<ws>/projects/<pid>/diagnostics?issue=<id>")

A link copied from the Opik UI works as the id: a thread link or a Diagnostics page link carries the project, so no project_id is needed and the entity type is taken from the link.