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How to evaluate audit logs and observability for trading agents through one API

A single API produces one audit trail across markets. Learn how to read those logs, set alerts, and verify that your agent stays within its guardrails.

By the Felix team11 min read
Key takeaways
  • 01A single API produces a unified audit trail across stocks, crypto, perps, options, and prediction markets, which is the only way to verify agent behavior without parsing fragmented venue logs.
  • 02Classify every log entry as a planned action, an exception, or a guardrail event, and review each category on its own dashboard to spot drift quickly.
  • 03The unified request ID lets you trace an agent's intent from model output through API validation to venue fill, closing the loop between decisions and economic outcomes.
  • 04Set alerts on guardrail events, API rejections, drawdown thresholds, key utilization anomalies, and latency spikes, not on every routine order.
  • 05Use historical audit logs to refine guardrail versions quantitatively, but test any relaxed limit in paper trading before applying it to live capital.

A single API that routes orders to stocks, crypto, perpetual futures, options, and prediction markets produces one chronological audit trail. That trail is the definitive record of what the agent decided, what the API permitted, and what the venues executed. Learning to read that trail is not optional. It is the primary way an owner verifies that the agent is operating within its budget, position limits, and approved withdrawal addresses.

What does a unified audit trail look like across five market types?

When an agent trades through separate venue accounts, logs fragment across different formats, timestamps, and identifiers. A single API normalizes this into a common schema. Every intent, from a stock order at a stock broker to a perp position at a perps venue, is logged in the same sequence with the same field definitions. The normalized record typically includes several standard fields. There is a timestamp in UTC that marks when the agent submitted the intent. There is a unique request ID that follows the order from agent intent through API validation to venue acknowledgement. The market type is explicitly labeled, whether it is stocks, crypto, perps, options, or prediction markets. The intended action is recorded alongside the size in plain US dollars, the instrument identifier, and the direction. The outcome is also logged, showing whether the order was accepted, rejected by the API, rejected by the venue, partially filled, or fully filled. Finally, the agent context is preserved, such as the MCP session ID or the REST API key scope that authorized the request. Because the API enforces guardrails before an order leaves the system, the log also contains a preflight check result. You can see whether the order passed budget caps, position limits, and the kill switch status at the exact moment of submission. This is critical because the log becomes evidence that the safety controls were active, not just configured. If an order is rejected by the API, the reason is stored in the same schema, so you do not need to parse different error codes from different venues. The presence of a unified schema also means that third party analysis tools, from simple spreadsheet scripts to full observability platforms, can ingest the stream without custom adapters for each venue. This reduces the engineering work required to stand up monitoring and makes it easier to replace or add venues later without rewriting your dashboards.

How should you structure logs to catch agent errors quickly?

Raw logs are verbose. The goal is to derive signals that tell you whether the agent is drifting from its intended behavior. Start by classifying every log entry into one of three categories: planned actions, exceptions, and guardrail events. Planned actions are orders that match the agent's strategy and fall within normal parameters. They represent the baseline behavior you expect during typical market conditions. Exceptions are orders that the agent submitted but the API rejected, or orders that returned unexpected errors from a venue. These exceptions reveal prompt drift, model confusion, or data feed errors that cause the agent to request invalid symbols, sizes, or directions. Guardrail events are interventions initiated by the API itself, such as truncating position size to fit a limit, blocking a withdrawal attempt to an unapproved address, or triggering the panic switch to flatten positions. For each category, you should maintain a separate dashboard or query view. The planned actions view helps you reconcile daily profit and loss against your expectations. The exceptions view reveals where the agent's reasoning is breaking down. The guardrail events view shows how often the agent is bumping into its boundaries. A sudden spike in guardrail events usually means the agent's strategy has changed, or the market environment has shifted outside the parameters you modeled during testing. When reviewing exceptions, look for patterns in timing and market context. If the agent starts sending malformed requests immediately after a macroeconomic news event, the model may be reacting to unstructured text rather than clean market data. This is where a reliable market data pipeline matters. Correlating exceptions against data quality logs helps you decide whether the problem is the agent's reasoning or the inputs it received. You should also look at exception frequency relative to total orders. Suppose an exception rate of five percent in options may be normal if the agent is probing for liquidity, while the same rate in stocks may indicate a fundamental data mapping error. A rising exception rate is a sign that the agent is degrading, not adapting.

Which observability signals matter most for live trading?

Observability is more than storing logs. It is the ability to ask arbitrary questions about system behavior in real time. For a trading agent, the most important signals are order latency, fill rate, slippage estimate, drawdown trajectory, and key utilization. Order latency measures the time between the agent's intent timestamp and the venue acknowledgement timestamp. A sudden increase in latency across one market type but not others may indicate a venue issue or a network partition, not a bug in the agent. You should track latency percentiles rather than averages, because a single outlier can distort the mean. Fill rate tracks how many submitted orders reached the venue and were executed versus rejected or cancelled. A dropping fill rate is an early warning that the agent is requesting prices or sizes that the venue considers invalid, or that liquidity has dried up in the instruments the agent is targeting. Slippage estimate compares the intended dollar size against the actual notional value of the fill. Because the API sizes orders in plain US dollars, you can compute this uniformly across stocks and crypto contracts without learning each venue's contract multiplier. A consistent slippage pattern that favors the agent is worth investigating just as much as negative slippage, because it may indicate a data lag or a fill reporting error. Drawdown trajectory is a continuous calculation of unrealized losses against the starting budget. The audit log provides the raw position data, and your observability layer should compute running drawdown. Drawdown trajectory should be calculated both on an absolute dollar basis and as a percentage of the starting budget for that trading period. This dual view prevents a small absolute loss from looking harmless when it represents a large fraction of a constrained account. If drawdown approaches the limit you set in the exit plan, the system should alert before the limit triggers the automatic kill switch. The alert gives you a window to review whether the agent is genuinely wrong or simply caught in a temporary market move. Key utilization is a security signal. It tracks which scopes are active, how many requests each key issues, and whether any keys are approaching their rate limits. Key utilization should be tracked per scope. If a key scoped only to read market data suddenly starts submitting orders, that is an immediate security event requiring rotation. Unusual key utilization patterns can indicate that the agent is stuck in a loop, or that an unauthorized client has obtained partial access. Because the API uses scoped keys, you can see exactly which permissions were exercised and when.

How do you correlate agent decisions with actual fills and PnL?

The hardest part of agent observability is closing the loop between the model's reasoning and the economic outcome. The unified request ID is the join key. Every log entry, from the initial prompt completion that generated the trade idea through the API order request to the venue fill report, should carry the same ID or a traceable parent ID. Start by mapping the agent's decision log. If the agent uses an MCP tool, the tool call contains the parameters the model chose. If the agent uses the REST API directly, the request body contains the same information. Compare these parameters to the audit log. Did the model request a buy, but the API log shows a sell? That is a critical bug in prompt parsing or tool invocation. Did the model request five hundred dollars, but the API log shows five thousand dollars? That suggests a unit conversion error or a prompt injection that altered the numeric field. Next, map the API log to the fill report. The API may accept an order, but a venue may only partially fill it or reject it at the clearing layer. The audit log should capture both the API acceptance and the venue response. If the venue response is missing for longer than the expected latency window, you have an orphaned order that needs manual inspection. The exact request schema is in the docs; the shape looks like this:

{
  "api_key": "YOUR_KEY",
  "scope": "audit:read",
  "trace_id": "YOUR_TRACE_ID",
  "include": ["agent_intent", "api_preflight", "venue_fill", "guardrail_version"]
}

Finally, map fills to profit and loss. Because the API normalizes contract math, you can aggregate fills across all five market types into a single running balance. This lets you answer questions like how much of the daily budget was consumed by prediction market bets versus perps positions, without writing separate parsers for each venue's fee schedule. It also lets you see whether the agent is concentrating risk in one market type while you believed it was diversified.

What is the right way to set alerts and review cadence?

Alerts should be actionable. An alert that fires every time the agent places an order is noise. An alert that fires when the agent places its first order outside approved market hours, or when it requests a size that exceeds the position limit by any amount, is a signal. Configure alerts around the following thresholds. First, any guardrail event, especially a panic switch trigger, because it means the agent has reached a boundary that you predefined as dangerous. Second, any order rejection by the API, because the agent should not be making requests that violate its own constraints. A pattern of rejections means the model and the limits are misaligned. Third, a drawdown threshold that is tighter than the automatic kill switch limit, giving you time to review before the system flattens positions. Fourth, a key utilization anomaly, such as a burst of requests far above the key's historical baseline. Fifth, a latency spike greater than three times the rolling average for that market type, which can indicate infrastructure stress. For review cadence, run an automated report every 24 hours that summarizes total orders, exceptions, guardrail events, and realized profit and loss. Review this report before authorizing the agent for the next trading session. If you are moving from paper trading to live trading, increase the review frequency to every four hours for the first two weeks. Paper trading logs are identical in structure to live logs, so the transition is mainly a matter of tightening alert thresholds and adding human sign-off steps. The article on moving to live trading covers that authorization process in more detail. You should also maintain a manual review checklist for your first month of live trading. The checklist includes verifying that the panic switch tested successfully during paper trading, confirming that withdrawal addresses have not changed, and sampling a random subset of orders to ensure the trace ID connects the agent decision to the fill report without gaps.

How do you use audit logs to improve guardrails over time?

Audit logs are not just for incident response. They are the feedback loop that makes guardrails better. Over weeks of operation, you will see where the agent consistently bumps into limits. Perhaps it repeatedly hits the perp position cap during high volatility, or it tries to trade options at times when liquidity is thin and the API rejects the orders. Analyze these patterns quantitatively. Count the frequency of each rejection reason. If the agent is rejected for insufficient margin far more often than any other reason, your margin buffer may be too tight for the strategy, or the strategy may be taking correlated risk across multiple venues that you did not intend. Adjust the guardrails based on this evidence, not on intuition. Remember that trading can lose money, including everything, so any adjustment that widens a limit should be tested in paper trading first. Also review the timing of successful trades relative to guardrail events. If the agent consistently makes its best trades shortly after a guardrail event, the limit may be forcing a delay that accidentally improves timing. If it consistently underperforms after a guardrail event, the limit may be interrupting a valid strategy. Use the logs to test hypotheses about cause and effect, but remember that trading outcomes are noisy. A single profitable trade after a rejection does not prove the rejection was beneficial. Look for patterns across dozens of events. As you refine the guardrails, version them. The audit log should record which guardrail version was active at the time of each order. This lets you compare agent behavior under different rule sets and roll back to a previous version if a new limit causes unexpected problems. This versioning is especially important when you manage risk across multiple markets, because a change in one market type can create hidden exposure in another.

Frequently asked questions

Can I view logs from paper trading and live trading in the same interface?

Yes. The unified API produces the same schema for both environments. You can query them together or filter by environment tag, which helps you compare agent behavior before and after authorization.

How long should I retain audit logs for a trading agent?

Retain them for as long as you need to reconcile taxes, verify strategy performance, or investigate disputes. The API stores them by default, but you should also export them to your own storage for redundancy and long term analysis.

What is the difference between a rejection by the API and a rejection by the venue?

An API rejection means the order violated your guardrails, such as budget caps or position limits, and never reached the venue. A venue rejection means the order passed your guardrails but failed at the venue's clearing layer, often due to insufficient margin or liquidity.

Should I alert on every API rejection?

Yes, but configure the alert priority. A single rejection is a low priority warning. Three or more rejections in one hour is a high priority signal that the agent is misaligned with its limits or the market has changed.

Can I trace an MCP tool call from Claude or Cursor through to the final fill?

Yes. The API logs include the MCP session ID or tool call ID as part of the agent context. You can use this as a parent trace ID to follow the full lifecycle from model output to economic outcome.

Do I need a separate observability tool, or does the API provide dashboards?

The API provides the normalized audit stream. Most owners feed this stream into their own observability platform to build custom dashboards, set alerts, and correlate with external data sources. The docs describe the available export formats.

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