Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add infraspecdev/tesseract --skill error-observability-reviewgit clone --depth 1 https://github.com/infraspecdev/tesseractWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/infraspecdev/tesseract/error-observability-review)<a href="https://agentmods.dev/skills/infraspecdev/tesseract/error-observability-review"><img src="https://agentmods.dev/badge/skills/infraspecdev/tesseract/error-observability-review/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/infraspecdev/tesseract/error-observability-review"><img src="https://agentmods.dev/badge/skills/infraspecdev/tesseract/error-observability-review.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00046 | $0.00973 |
| Opus 5.5 | $0.00018 | $0.00389 |
| Sonnet 5.5 | $0.00009 | $0.00195 |
| Haiku 4.5 | $0.00005 | $0.00097 |
Grade A, and why
backend-error-observability-review scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 78 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Backend Error & Observability Review
Overview
Review backend code for proper error handling and observability instrumentation: exception type design, propagation patterns, logging discipline (level, structure, context), metric coverage, trace context propagation, and correlation ID hygiene.
Framework-agnostic: applies to Spring @ControllerAdvice, FastAPI exception handlers, Express error middleware, Go error wrapping, etc.
When to Use
- Reviewing exception handlers, error response shapers
- Reviewing services that perform IO (DB, HTTP, queue)
- Auditing observability gaps in a critical path
- Pre-implementation: shaping error contract during planning
When NOT to Use
- Pure infra-level monitoring config — different skill
- Frontend error handling — backend-specific patterns may not apply
Review Process
- Inventory: exception handlers, try/catch blocks, log calls, metric/trace instrumentation
- For each, apply Evaluation Points E1–E10
- Cross-cut: trace a request path and check that every IO point has structured logging + error path
Evaluation Points
| # | Check | What to Look For | Severity |
|---|---|---|---|
| E1 | Exception type design | Domain-specific exception types (e.g., OrderNotFoundException), not bare RuntimeException for everything |
Medium |
| E2 | No catch-all that maps to 5xx | Catching Throwable/Exception and returning 500 hides client errors. Map by type |
High |
| E3 | No silent swallows | Every catch either rethrows, logs at appropriate level, increments a metric, or transforms to a domain result. Empty catches are bugs |
High |
| E4 | Exception-as-control-flow avoidance | Don't throw + catch within the same method to drive branching. Use return values or guard clauses | Medium |
| E5 | Log level discipline | DEBUG for trace, INFO for state transitions, WARN for recoverable issues, ERROR for true failures. Flag println or System.err |
High |
| E6 | Structured logging | Logs use key-value/JSON, not string concatenation. Flag log.info("user " + id + " did " + action) |
Medium |
| E7 | Correlation/trace context | Logs include request/trace ID. Distributed services propagate trace headers | High |
| E8 | Metric coverage on critical paths | Counter on errors per endpoint, latency histogram on external calls, business metrics on key flows | Medium |
| E9 | No internal details in error responses | Don't return stack traces, SQL fragments, or framework messages to clients | High |
| E10 | Idempotency on retried error paths | When retrying after a transient error, the operation must be safe to repeat | Medium |
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 78 lines · 46 tokens per session scan A a6d7e3994536
backend-error-observability-review is a skill published in the GitHub repository infraspecdev/tesseract (5 stars, last pushed 3mo ago), licensed MIT. It adds 46 tokens to every session and 973 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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