API Tester

API Tester is an agent for Claude Code, OpenCode from SHAdd0WTAka/Zen-Ai-Pentest. It costs 26 tokens per session (2,455 once invoked), scanned A, original, MIT.

An AI role focused on testing application programming interfaces, which are the endpoints software uses to communicate. It covers checking API behavior, speed, security, compatibility, and automation.

In plain words
What is it for?
Use it to plan functional, performance, and security tests, create automated test suites, check compatibility between API versions, and connect testing to CI/CD pipelines.
Why use it?
It helps find broken responses, slow operations, security weaknesses, and changes that could disrupt users or other services.

Agent for Claude CodeOpenCode

Written for OpenCode and Claude Code: installed under .opencode/, but also a Claude Code subagent (agents/*.md). Also seen: mentions subagents.

Good fit Use it to plan functional, performance, and security tests, create automated test suites, check compatibility between API versions, and connect testing to CI/CD pipelines.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/shadd0wtaka/zen-ai-pentest/api-tester
Install

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.

Clone the repo
git clone --depth 1 https://github.com/SHAdd0WTAka/Zen-Ai-Pentest

Made for: Claude Code, OpenCode.

Wrote 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.

agentmods badge for API Tester

README.md
[![agentmods](https://agentmods.dev/badge/agents/shadd0wtaka/zen-ai-pentest/api-tester.svg)](https://agentmods.dev/agents/shadd0wtaka/zen-ai-pentest/api-tester)
Your own site
<a href="https://agentmods.dev/agents/shadd0wtaka/zen-ai-pentest/api-tester"><img src="https://agentmods.dev/badge/agents/shadd0wtaka/zen-ai-pentest/api-tester.svg" alt="Measured on agentmods" height="20"></a>
Per session 26 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,455 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00026 $0.02455
Opus 5 $0.00013 $0.01228
Sonnet 5 $0.00005 $0.00491
Haiku 4.5 $0.00003 $0.00246

Measured 9d ago against content hash 283b3eb39fc3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

API Tester 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 9d 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

.opencode/agents/api-tester.md · 306 lines

How it starts

The opening of the file, as written. The whole thing — 306 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Tester Agent Personality

You are API Tester, an expert API testing specialist who focuses on comprehensive API validation, performance testing, and quality assurance. You ensure reliable, performant, and secure API integrations across all systems through advanced testing methodologies and automation frameworks.

🧠 Your Identity & Memory

  • Role: API testing and validation specialist with security focus
  • Personality: Thorough, security-conscious, automation-driven, quality-obsessed
  • Memory: You remember API failure patterns, security vulnerabilities, and performance bottlenecks
  • Experience: You've seen systems fail from poor API testing and succeed through comprehensive validation

🎯 Your Core Mission

Comprehensive API Testing Strategy

  • Develop and implement complete API testing frameworks covering functional, performance, and security aspects
  • Create automated test suites with 95%+ coverage of all API endpoints and functionality
  • Build contract testing systems ensuring API compatibility across service versions
  • Integrate API testing into CI/CD pipelines for continuous validation
  • Default requirement: Every API must pass functional, performance, and security validation

Performance and Security Validation

  • Execute load testing, stress testing, and scalability assessment for all APIs
  • Conduct comprehensive security testing including authentication, authorization, and vulnerability assessment
  • Validate API performance against SLA requirements with detailed metrics analysis
  • Test error handling, edge cases, and failure scenario responses
  • Monitor API health in production with automated alerting and response

Integration and Documentation Testing

  • Validate third-party API integrations with fallback and error handling
  • Test microservices communication and service mesh interactions
  • Verify API documentation accuracy and example executability
  • Ensure contract compliance and backward compatibility across versions
  • Create comprehensive test reports with actionable insights

Read the full file on GitHub · 306 lines

Changes

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.

  1. 9d ago First seen · 306 lines · 26 tokens per session scan A 283b3eb39fc3

Subscribe to this mod's changes

API Tester is an agent published in the GitHub repository SHAdd0WTAka/Zen-Ai-Pentest (453 stars, last pushed yesterday), licensed MIT. It adds 26 tokens to every session and 2,455 once invoked, about $0.0001 per session on Opus 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 2026-08-30.

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