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 agentmods add rules/altaidevorg/rules-for-ai/apierrorgit clone --depth 1 https://github.com/altaidevorg/rules-for-aiWhat 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 | $0.00000 | $0.03465 |
| Opus 5 | $0.00000 | $0.01733 |
| Sonnet 5 | $0.00000 | $0.00693 |
| Haiku 4.5 | $0.00000 | $0.00347 |
Grade A, and why
apierror 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 2d 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 — 259 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Chapter 9: APIError
In Chapter 8: BaseApiClient, we examined the core component responsible for handling HTTP communication with the Google Generative AI APIs. We saw that BaseApiClient sends requests and receives responses. But what happens when the API service itself encounters an error and returns a non-successful HTTP status code (like 400 Bad Request or 500 Internal Server Error)? This chapter introduces APIError, the structured exception class designed specifically for handling these API-level errors.
Motivation and Use Case
When interacting with any external service, robust error handling is critical. Network issues, invalid inputs, temporary service outages, or permission problems can all lead to failed API calls. Simply relying on generic Python exceptions (like httpx.HTTPStatusError) wouldn't provide enough specific information about why the API call failed from the service's perspective. Developers need a way to:
- Distinguish API Service Errors: Differentiate errors originating from the Google GenAI service (e.g., invalid API key, malformed request, resource not found) from general network or Python runtime errors.
- Access Structured Error Details: Retrieve specific error information provided by the API, such as an error code, a descriptive message, and a status identifier (e.g., 'INVALID_ARGUMENT', 'PERMISSION_DENIED').
- Implement Targeted Error Handling: Write
try...exceptblocks that specifically catch API-related issues and potentially implement different logic based on the error details (e.g., retrying on transient server errors, logging specific client errors).
APIError and its subclasses (ClientError, ServerError) fulfill these needs by providing a dedicated exception hierarchy for errors returned by the Google GenAI API.
Central Use Case: Imagine you make an API call with an invalid parameter, such as referencing a non-existent model. The API will return a 4xx error. Your code should be able to catch this specific type of error and extract the details provided by the API.
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.
- 2d ago First seen · 259 lines · 0 tokens per session scan A ee0cf5d4b332
apierror is a cursor rule published in the GitHub repository altaidevorg/rules-for-ai (2 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 3,465 tokens. 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 2026-08-31.
Other cursor rules, from other repositories
angular-20
This rule provides comprehensive best practices and coding standards for Angular development, focusing on modern TypeScript, standalone components, signals, and performance optimizations.
dev-standard
Apache Superset development standards and guidelines for Cursor IDE.
cli-error-handling
CLI command error handling patterns.
prefer-direct-imports-over-module-mocks
Prefer extracting a testable core over vi.mock / vi.resetModules when unit tests need to reach production logic entangled with config, env, or singletons.
control-plane-descriptors
Control plane descriptor and instance implementation patterns.
family-instance-domain-actions
Family instance domain action implementation patterns.