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 skills/xalgorix/xalgorix/implementing-api-schema-validation-securitynpx skills add xalgorix/xalgorix --skill implementing-api-schema-validation-securitygit clone --depth 1 https://github.com/xalgorix/xalgorixWrote 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/xalgorix/xalgorix/implementing-api-schema-validation-security)<a href="https://agentmods.dev/skills/xalgorix/xalgorix/implementing-api-schema-validation-security"><img src="https://agentmods.dev/badge/skills/xalgorix/xalgorix/implementing-api-schema-validation-security.svg" alt="Measured on agentmods" 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 | $0.00035 | $0.03284 |
| Opus 5 | $0.00017 | $0.01642 |
| Sonnet 5 | $0.00007 | $0.00657 |
| Haiku 4.5 | $0.00003 | $0.00328 |
Grade A, and why
implementing-api-schema-validation-security scanned grade A with 1 finding 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 4d 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
curl -X POST "https://api.cloudflare.com/client/v4/zones/{zone_id}/api_gateway/user_schemas" \ How it starts
The opening of the file, as written. The whole thing — 441 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Implementing API Schema Validation Security
Overview
API schema validation enforces that all data exchanged through APIs conforms to a predefined structure defined in OpenAPI Specification (OAS) or JSON Schema documents. This prevents injection attacks (SQLi, XSS, XXE), blocks mass assignment by rejecting unknown properties, prevents data leakage by validating response schemas, and ensures type safety across all API interactions. Schema validation operates at both the API gateway level (runtime enforcement) and during development (shift-left security).
When to Use
- When deploying or configuring implementing api schema validation security capabilities in your environment
- When establishing security controls aligned to compliance requirements
- When building or improving security architecture for this domain
- When conducting security assessments that require this implementation
Common Misconfigurations & Verification
additionalPropertiesmissing or true: the single most common gap - withoutadditionalProperties: false, mass-assignment fields pass validation; set it on every object schema.- Request-only validation: validating input but not responses lets excessive-data-exposure through; validate/serialize responses with explicit DTOs.
- Loose constraints: strings without
maxLength/patternand fields withoutenumpermit injection and DoS payloads. readOnlynot enforced server-side: clients can still write readOnly fields if the server only documents them rather than rejecting them.- Permissive/verbose errors: leaking schema detail in 400 responses aids attackers.
- Spec drift: the deployed schema lagging the live API leaves new endpoints unvalidated.
How to verify it works: send a request with an extra/unknown field and confirm 400 (not silent acceptance); submit over-long and pattern-violating values and confirm rejection; attempt to set a readOnly field and confirm it is ignored; force a sensitive field into a response and confirm response validation strips it or fails safely; diff the enforced spec against the live route list.
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.
- 4d ago First seen · 441 lines · 35 tokens per session scan A 600ffe30ca28
implementing-api-schema-validation-security is a skill published in the GitHub repository xalgorix/xalgorix (955 stars, last pushed today), licensed Apache-2.0. It adds 35 tokens to every session and 3,284 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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