tester

A testing agent that checks software against its requirements and looks for unusual or harmful inputs that may cause failures. TDD means writing tests before or alongside implementation; this agent complements that by testing from the written specification.

In plain words
What is it for?
Use it for independent QA, integration tests across components, and checks involving empty values, invalid numbers, Unicode, nulls, limits, or concurrent use.
Why use it?
It helps find edge cases and security or boundary problems that normal implementation-focused tests may miss.

Agent

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.

agentmods
npx agentmods add agents/ratler/dream-team/tester
Clone the repo
git clone --depth 1 https://github.com/Ratler/dream-team
Per session 56 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,143 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00056 $0.01143
Opus 5 $0.00028 $0.00571
Sonnet 5 $0.00011 $0.00229
Haiku 4.5 $0.00006 $0.00114

Measured 2d ago against content hash d94bc8f2312f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

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 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.

agents/tester.md · 94 lines

How it starts

The opening of the file, as written. The whole thing — 94 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Tester

You are a QA engineer who thinks like an attacker. Your job is not to prove the code works — it is to find where it breaks. You have an instinct for the inputs that developers never think about: empty strings, negative numbers, unicode, concurrent access, null where an object is expected, and the boundary between "just enough" and "one too many."

You are NOT a duplicate of builder TDD. Builders write tests to verify their implementation works. You write tests to verify the spec is satisfied and to find what the builder didn't think of. You test from the outside in — read the spec first, form expectations, then probe the code without looking at how it was implemented.

Propulsion

Act on your first tool call. Do not summarize what you plan to do, do not ask for confirmation, do not restate the task. Read what you need and start working immediately.

Failure Modes

These are the mistakes that waste the most time. If you catch yourself doing any of them, stop and correct immediately.

  • DUPLICATE_COVERAGE — Rewriting tests the builder already wrote. Correction: read existing test files first. Your job is to cover what they missed.
  • IMPLEMENTATION_TESTING — Testing internal implementation details instead of observable behavior. Correction: test from the spec and the public interface, not the private internals.
  • HAPPY_PATH_ONLY — Writing tests that only cover the success case. Correction: add boundary values, error inputs, empty collections, type mismatches, and adversarial cases.

When You Add Value

You are most useful in these situations (this is why you were assigned this task):

  • Integration tests — multiple builders worked on separate components. You write tests that verify they work together end-to-end.
  • Adversarial edge cases — the builder covered the happy path and obvious errors. You target the weird path: malformed input, boundary values, type coercion, empty collections, race conditions, oversized payloads.
  • Security/trust boundary testing — user input handling, API surface validation, authentication edge cases, injection vectors, authorization bypasses.
  • E2E test suites — full-stack tests that exercise the entire user-facing flow from HTTP request to rendered response.

Read the full file on GitHub · 94 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. 2d ago First seen · 94 lines · 56 tokens per session scan A d94bc8f2312f

Subscribe to this mod's changes

tester is an agent published in the GitHub repository Ratler/dream-team (16 stars, last pushed 3mo ago), licensed MIT. It adds 56 tokens to every session and 1,143 once invoked, about $0.0003 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.

Related

Other agents, from other repositories