Manage Cursor Tracing

Setup Cursor Tracing

Configure OpenInference tracing for Cursor IDE sessions to Arize AX (cloud) or Phoenix (self-hosted). Spans are sent directly to the backend from hooks -- no background process or backend-specific dependencies are needed in the user's environment.

How to Use This Skill

This skill follows a decision tree workflow. Start by asking the user where they are in the setup process:

1. First, determine the install type. Was Arize tracing installed as a Cursor plugin (via /add-plugin in Cursor 2.5+, which registers hooks automatically), or manually by running install.sh?

   • If unsure, ask the user directly: "Did you install Arize tracing as a Cursor plugin (via /add-plugin), or by running install.sh?"
   • Heuristic 1: Check Cursor's installed-plugins location for a cursor-tracing plugin directory.
   • Heuristic 2: Check whether .cursor/hooks.json already contains arize-hook-cursor entries -- if so, this is a manual install.sh install; if absent, it's a plugin install (or a fresh setup).
   • This branch only matters for the Activate Cursor hooks step below. The credentials/config step is identical for both install types.

2. Do they already have credentials?

   • Yes -> Jump to Configure Settings
   • No -> Continue to step 3

3. Which backend do they want to use?

   • Phoenix (self-hosted) -> Go to Set Up Phoenix
   • Arize AX (cloud) -> Go to Set Up Arize AX

4. Are they troubleshooting?

   • Yes -> Jump to Troubleshoot

Important: Only follow the relevant path for the user's needs. Don't go through all sections.

Plugin users, please read: The marketplace install via /add-plugin registers Cursor hooks automatically but cannot run an interactive credentials wizard. Run this skill once after /add-plugin so it can write ~/.arize/harness/config.json with your backend credentials -- without that file, the hooks will fail open (no-op) and no spans will be sent.

Set Up Phoenix

Phoenix is self-hosted. No Python dependencies are needed for tracing -- spans are sent directly via send_span() using stdlib urllib.

Install Phoenix

Ask if they already have Phoenix running. If not, walk through:

# Option A: pip
pip install arize-phoenix && phoenix serve

# Option B: Docker
docker run -p 6006:6006 arizephoenix/phoenix:latest

Phoenix UI will be available at http://localhost:6006. Confirm it's running:

curl -sf http://localhost:6006/v1/traces >/dev/null && echo "Phoenix is running" || echo "Phoenix not reachable"

Then proceed to Configure Settings with the Phoenix endpoint.

Set Up Arize AX

Arize AX is available as a SaaS platform or as an on-prem deployment. Users need an account, a space, and an API key.

First, ask the user: "Are you using the Arize SaaS platform or an on-prem instance?"

• SaaS -> Uses the default endpoint (otlp.arize.com:443). Continue below.
• On-prem -> The user will need to provide their custom OTLP endpoint (e.g., otlp.mycompany.arize.com:443). Ask for it and note it for the Configure Settings step.

1. Create an account

If the user doesn't have an Arize account:

• SaaS: Sign up at https://app.arize.com/auth/join
• On-prem: Contact their administrator for access to the on-prem instance

2. Get Space ID and API key

Walk the user through finding their credentials:

1. Log in to their Arize instance (https://app.arize.com for SaaS, or their on-prem URL)
2. Click Settings (gear icon) in the left sidebar
3. The Space ID is shown on the Space Settings page
4. Go to the API Keys tab
5. Click Create API Key or copy an existing one

Both api_key and space_id are required for the shared config.

No Python dependencies are needed. Both Phoenix and Arize AX use HTTP/JSON — no additional Python dependencies are needed.

Then proceed to Configure Settings. If the user is on an on-prem instance, remind them to provide their custom endpoint.

Configure Settings

Important: Users must run this setup before tracing will work. The send_span() function requires ~/.arize/harness/config.json to exist for backend credential resolution.

Ask the user for:

1. Backend choice: Phoenix or Arize AX
2. Credentials (only if no existing config):
   • Phoenix: endpoint URL (default: http://localhost:6006), optional API key
   • Arize AX: API key and Space ID
3. OTLP Endpoint (Arize AX only, optional): For hosted Arize instances using a custom endpoint. Defaults to otlp.arize.com:443.
4. Project name (optional): defaults to "cursor", stored under harnesses.cursor.project_name
5. User ID (optional): Set ARIZE_USER_ID env var to identify spans by user (useful for teams)

Write the config

The config file at ~/.arize/harness/config.json is the single source of truth for backend credentials and per-harness settings. Create the directory structure if needed: mkdir -p ~/.arize/harness/{bin,run,logs,state/cursor}

Important: read-merge-write. If ~/.arize/harness/config.json already exists, read it first, then merge in the new or updated fields (e.g., add/update the harnesses.cursor entry) while preserving existing backend credentials. Only prompt for backend credentials if no existing config is found.

Phoenix:

{
  "harnesses": {
    "cursor": {
      "project_name": "cursor",
      "target": "phoenix",
      "endpoint": "<endpoint>",
      "api_key": ""
    }
  }
}

Arize AX:

{
  "harnesses": {
    "cursor": {
      "project_name": "cursor",
      "target": "arize",
      "endpoint": "otlp.arize.com:443",
      "api_key": "<key>",
      "space_id": "<id>"
    }
  }
}

If the user has a custom OTLP endpoint, set it in harnesses.cursor.endpoint.

Activate Cursor hooks

This step depends on install type (see How to Use This Skill step 1). Pick the branch that matches the user's install:

Plugin install (Cursor /add-plugin)

Skip this step entirely. The plugin's bundled hooks/hooks.json already registers every Cursor hook event automatically when the plugin is installed. There is nothing to write to .cursor/hooks.json.

After saving credentials in the previous step, tell the user to start a new Cursor session -- traces will begin flowing on the next interaction.

Warning: Do NOT manually add .cursor/hooks.json entries on top of a plugin install. Cursor will then route each event to the handler twice (once via the plugin and once via your project file), producing duplicate spans for every hook. If the user already has manual .cursor/hooks.json entries pointing at arize-hook-cursor from a previous install.sh setup, remove those entries before relying on the plugin.

Manual install (install.sh)

Cursor uses a .cursor/hooks.json file in the project root to route hook events to the handler. All events route to a single arize-hook-cursor CLI entry point, which dispatches based on hook_event_name in the JSON payload.

Create .cursor/hooks.json in the user's project (or merge into it if it already exists):

{
  "version": 1,
  "hooks": {
    "sessionStart": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "sessionEnd": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "beforeSubmitPrompt": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "afterAgentResponse": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "afterAgentThought": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "beforeShellExecution": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "afterShellExecution": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "beforeMCPExecution": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "afterMCPExecution": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "beforeReadFile": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "afterFileEdit": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "stop": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "beforeTabFileRead": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "afterTabFileEdit": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "postToolUse": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }]
  }
}

If the user already has a .cursor/hooks.json with other hooks, merge the Arize entries into the existing arrays for each event.

Validate

1. Config exists: Run cat ~/.arize/harness/config.json to verify the config file exists and has correct backend credentials.
2. Phoenix (if applicable): Run curl -sf <endpoint>/v1/traces >/dev/null to check connectivity.
3. Hooks active:
   • Manual install: Verify .cursor/hooks.json exists in the project root and contains the Arize hook entries.
   • Plugin install: No project-level .cursor/hooks.json is required -- the plugin registers hooks itself. Confirm the cursor-tracing plugin is listed as installed in Cursor.

Confirm

Tell the user:

• Config saved to ~/.arize/harness/config.json
• Cursor hooks activated via .cursor/hooks.json
• Spans are sent directly to the backend from hooks — no background process needed
• After saving, open a new Cursor session and traces will appear in their Phoenix UI or Arize AX dashboard under the project name
• Mention ARIZE_DRY_RUN=true to test without sending data (set as env var before launching Cursor)
• Mention ARIZE_VERBOSE=true for debug output
• Errors are always written to ~/.arize/harness/logs/cursor.log; set ARIZE_VERBOSE=true in the shell before launching Cursor to also capture routine hook activity

Hook Events

IDE Hooks

Cursor IDE fires 15 hook events. Here's what each one traces:

Shell and MCP events use a disk-backed state stack to merge before/after context into single spans with both input and output.

CLI Hooks

Cursor CLI currently emits a smaller hook surface than the IDE. The supported CLI hooks in this package are:

• sessionStart
• sessionEnd
• beforeShellExecution
• afterShellExecution
• afterFileEdit
• postToolUse
• stop

Cursor CLI hooks do not currently emit afterAgentResponse or afterAgentThought.

Full Cursor CLI assistant and thinking coverage requires parsing --output-format stream-json, which is out of scope for this change.

What We Capture

• sessionStart produces a Session Start CHAIN span that acts as the root for the conversation.
• sessionEnd produces a Session End CHAIN span with cursor.session.duration_ms, cursor.session.final_status, cursor.session.reason, and end-of-session token counts when available.
• stop produces an Agent Stop CHAIN span carrying per-turn status / loop_count / duration metadata. On the Cursor IDE, per-turn token usage is attached to the Agent Response (LLM) span instead: that span is deferred from afterAgentResponse and sent at end-of-turn when stop fires, populated from the stop payload with llm.token_count.prompt (the total prompt — Cursor's input_tokens is the uncached remainder, so cache reads/writes are added back in), llm.token_count.completion, the OpenInference cache subsets llm.token_count.prompt_details.cache_read / llm.token_count.prompt_details.cache_write, llm.token_count.total, and llm.model_name. Cursor CLI does not emit afterAgentResponse, so there is no LLM span to attach to; for the CLI path, token counts remain on the Agent Stop / Session End CHAIN span as before.
• postToolUse produces a generic Tool: <name> span ONLY for tools without a dedicated handler. Shell, file read/edit, tab file ops, and MCP execution are handled by their dedicated before*/after* events; the generic postToolUse is suppressed for these to avoid duplicate spans.

Every span includes cursor.conversation.id as a span attribute. Since sessionStart and per-turn activity use different trace_id values, cursor.conversation.id is the recommended cross-trace join key in Arize. To gather all activity for a Cursor session regardless of trace, filter spans by attributes.cursor.conversation.id = "<id>".

Hooks JSON Example (IDE + CLI)

Plugin users: do NOT hand-write .cursor/hooks.json from this example. The example below is a reference for the manual install.sh path only. Under a Cursor /add-plugin install, the plugin's bundled hooks/hooks.json already registers every event automatically; adding these entries on top of the plugin would route each event to the handler twice and produce duplicate spans for every hook. See Activate Cursor hooks > Plugin install.

When configuring .cursor/hooks.json on a manual install.sh install, include both IDE and CLI events:

{
  "version": 1,
  "hooks": {
    "sessionStart": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "sessionEnd": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "beforeSubmitPrompt": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "afterAgentResponse": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "afterAgentThought": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "beforeShellExecution": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "afterShellExecution": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "beforeMCPExecution": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "afterMCPExecution": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "beforeReadFile": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "afterFileEdit": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "stop": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "beforeTabFileRead": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "afterTabFileEdit": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }],
    "postToolUse": [{ "command": "~/.arize/harness/venv/bin/arize-hook-cursor" }]
  }
}

Troubleshoot

Common issues and fixes: