Manage Kiro Tracing

Setup Kiro Tracing

Configure OpenInference tracing for Kiro CLI 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. Each traced session emits LLM turns, tool calls, cost in credits, model information, and turn duration.

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. Is the harness already installed?

   • Check ~/.kiro/agents/ for an agent file containing arize-hook-kiro in its hooks block
   • Check ~/.arize/harness/config.json for the harnesses.kiro block
   • If both are present → Jump to Validate or Troubleshoot

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.

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.

Configuration has two parts:

1. Backend config (~/.arize/harness/config.json) — backend credentials and per-harness settings, read by send_span().
2. Kiro agent config (~/.kiro/agents/<agent>.json) — the agent the user runs with, containing the tracing hooks block.

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 "kiro", stored under harnesses.kiro.project_name
5. User ID (optional): Set ARIZE_USER_ID env var to identify spans by user (useful for teams)
6. Agent name (Kiro-specific): defaults to arize-traced. The hooks are written into ~/.kiro/agents/<name>.json. Use an existing agent if the user wants to add tracing to their current workflow without switching agents.
7. Set as Kiro's default? (Kiro-specific): If yes, the installer runs kiro-cli agent set-default <name> so kiro-cli chat (no --agent flag) uses the traced agent.

Write the backend 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/kiro}

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.kiro entry) while preserving existing backend credentials. Only prompt for backend credentials if no existing config is found.

Phoenix:

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

Arize AX:

{
  "harnesses": {
    "kiro": {
      "project_name": "kiro",
      "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.kiro.endpoint.

Activate Kiro hooks

Kiro registers hooks per agent. Each agent is a JSON file under ~/.kiro/agents/<name>.json. The installer either creates the file fresh (default agent: arize-traced) or merges hooks into an existing agent the user picks.

A freshly-created arize-traced agent looks like:

{
  "name": "arize-traced",
  "description": "Kiro agent with Arize tracing hooks installed.",
  "prompt": null,
  "mcpServers": {},
  "tools": ["*"],
  "toolAliases": {},
  "allowedTools": [],
  "resources": [],
  "hooks": {
    "agentSpawn":       [{ "command": "~/.arize/harness/venv/bin/arize-hook-kiro" }],
    "userPromptSubmit": [{ "command": "~/.arize/harness/venv/bin/arize-hook-kiro" }],
    "preToolUse":       [{ "command": "~/.arize/harness/venv/bin/arize-hook-kiro" }],
    "postToolUse":      [{ "command": "~/.arize/harness/venv/bin/arize-hook-kiro" }],
    "stop":             [{ "command": "~/.arize/harness/venv/bin/arize-hook-kiro" }]
  },
  "toolsSettings": {},
  "includeMcpJson": true,
  "model": null
}

All five events route to a single arize-hook-kiro CLI entry point that dispatches based on the event name in the payload.

If the user already has an agent JSON they want to trace, merge the five entries above into its existing hooks block — do not overwrite the rest of the agent definition.

To install or reinstall via the installer:

./install.sh kiro

To uninstall (removes only the Arize hook entries from each agent file; deletes the agent file only if the installer created it):

./install.sh uninstall kiro

Set as default agent (optional)

If the user wants kiro-cli chat to use the traced agent automatically:

kiro-cli agent set-default arize-traced

Otherwise, they explicitly pass --agent:

kiro-cli chat --agent arize-traced

Validate

1. Config exists: Run cat ~/.arize/harness/config.json to verify the file contains the harnesses.kiro block.
2. Agent file exists: Run cat ~/.kiro/agents/<agent>.json to verify the hooks block has all five events pointing at arize-hook-kiro.
3. Phoenix (if applicable): Run curl -sf <endpoint>/v1/traces >/dev/null to check connectivity.
4. Kiro accepts the agent config (optional, requires kiro-cli on PATH): kiro-cli agent validate --path ~/.kiro/agents/<agent>.json.

Confirm

Tell the user:

• Backend config saved to ~/.arize/harness/config.json
• Tracing hooks registered in ~/.kiro/agents/<agent>.json
• Run a session with kiro-cli chat (if you set it as default) or kiro-cli chat --agent <agent>
• Spans are sent directly to the backend from hooks — no background process needed
• 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 Kiro)
• Mention ARIZE_VERBOSE=true for debug output
• Errors are always written to ~/.arize/harness/logs/kiro.log; set ARIZE_VERBOSE=true in the shell before launching Kiro to also capture routine hook activity

Hook Events

Kiro fires 5 hook events. The first three accumulate state; only postToolUse and stop emit spans.

Span attributes (LLM span)

Span attributes (TOOL span)

TOOL spans are parented to the LLM turn they belong to via the FIFO tool-state stack.

Known limitations

• Token counts are typically 0. Kiro currently meters in credits, not tokens. Token count attributes are omitted when the value is 0. See kiro.cost.credits for usage tracking instead.
• FIFO tool matching. Kiro does not expose a tool-call ID, so pre/post tool events are matched using a FIFO stack. This assumes serial tool execution within a session — concurrent tool calls would mismatch.
• Sidecar read is fail-soft. The session sidecar at ~/.kiro/sessions/cli/<session_id>.json may not exist or may lag behind hook events due to a flush race. When this happens, the LLM span is emitted with basic attributes only (no model name, cost, or duration).

Troubleshoot

Common issues and fixes: