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LV2 · Toolooo Standard
Explore → See → Understand → ActUnderstand it. Feature Level describes the depth of the tool experience.

API Error Contract Builder

Create consistent API errors with RFC 9457 JSON, safe messages and client recovery guidance.

EngineeringAPIBackendSecurityReliability
🔒Your tool inputs are processed in your browser and are not uploaded or sent to analytics.

Define a safe public error, then generate the JSON and client recovery plan. Use fictional data. Definitions stay in memory; copy/download includes the reviewed public text you enter.

1/12 error definitions. Loading an example replaces only the selected definition.

Occurrence, retry header and correlation

Instance identifies an occurrence, not the problem class. Replace the fictional traceId at runtime with an opaque identifier; never attach diagnostic context. No telemetry integration runs.

Field validation messages (1/10)
Field error 1

Use /quantity or #/quantity. Messages describe a rule, not the submitted private value. The errors array and rule codes are custom extensions.

Example definitions are fictional and pre-reviewed. Review edits yourself: pattern checks cannot detect every secret or personal value.

What this tool does and why

Before you start

What

Create consistent API errors with RFC 9457 JSON, safe messages and client recovery guidance.

Why

Stable problem types and safe public messages help clients distinguish invalid input, permission failures and recoverable conditions without exposing implementation details.

Your Result and Action update in the tool as you change its inputs.

Model note

This browser-side model explains the inputs you choose. Check an important decision against the real system, brief, or production constraints.

Next

Use the result to choose a connected next move.

Retry Storm SimulatorCompare retry policies and see how attempts, backoff, jitter, and budgets change recovery pressure.MCP Tool Contract BuilderCreate bounded MCP input/output schemas with separate approval, scope, retry and failure guidance.
How this tool stays honest

How it works

Define stable problem types, HTTP statuses and public codes. Build a reviewed error catalog with field-validation extensions, retry classifications, idempotency warnings and safe client actions. Generate and export Problem Details locally without connecting an API.

Assumptions

The tool runs in your browser and models the information you provide. It does not know facts outside that model.

Limitations

Bounded RFC 9457 profile and heuristic security review, not middleware, runtime HTTP validation, complete secret detection or security certification. Status choices depend on actual semantics. Retry safety and deduplication require implementation; Problem Details is not mandatory for every API.

Understand API Error Contract Builder

What this tool helps you understand

Define stable problem types, HTTP statuses and public codes. Build a reviewed error catalog with field-validation extensions, retry classifications, idempotency warnings and safe client actions. Generate and export Problem Details locally without connecting an API.

When to use it

Before implementing consistent public API failures and client handling.

Try a scenario

Compare Validation Error with Rate Limited and Dependency Failure. Add a second error, choose a unique code, inspect retry safety and export only reviewed public Problem Details.

How to read the result

Resolve FAIL findings before export. Review WARN findings in context, align actual HTTP status and headers with the body, document custom extensions and implement the declared client recovery policy.

Assumptions and limits

Bounded RFC 9457 profile and heuristic security review, not middleware, runtime HTTP validation, complete secret detection or security certification. Status choices depend on actual semantics. Retry safety and deduplication require implementation; Problem Details is not mandatory for every API.

Toolooo is part of Khizooology, created byKhizar Imtiaz (khizooo).