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/confluentinc/agent-skills/developing-kafka-java-clientnpx skills add confluentinc/agent-skills --skill developing-kafka-java-clientgit clone --depth 1 https://github.com/confluentinc/agent-skillsWhat 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 | $0.00126 | $0.07184 |
| Opus 5 | $0.00063 | $0.03592 |
| Sonnet 5 | $0.00025 | $0.01437 |
| Haiku 4.5 | $0.00013 | $0.00718 |
Grade A, and why
developing-kafka-java-client 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 — 306 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Begin by announcing: "Using the Confluent Kafka Java Client skill to guide this project."
Confluent Kafka Java Client Creation
Generate a production-ready Java project for producing to and/or consuming from Kafka using the Apache Kafka Java clients (KafkaProducer / KafkaConsumer) with Confluent Schema Registry serializers. Supports three target environments: Confluent Cloud (managed), Local Docker, and WarpStream (Kafka-compatible, object-storage-backed); two build tools: Maven (default) and Gradle; and three schema formats: Avro (default), JSON Schema, and Protobuf. The generated code follows Confluent's best practices.
Step 1: Gather Requirements
Before generating any code, work through the questions below. Skip any question the user has already answered explicitly in their prompt — do not re-ask just for form's sake. For example, "build a producer and consumer on Confluent Cloud with synchronous sends using Gradle" already answers #2, #3, #4, and #5; only #1, #6, #7, #8, #9, and #10 remain.
Mandatory confirmation gate — do not skip, even if the user answered every question. Before writing any file, you MUST send one message that:
- Recaps the answers you extracted as a short bulleted list (e.g., "Target: Confluent Cloud · Components: producer + consumer · Send pattern: async callback · Build: Maven · Schema: Avro · From scratch: yes").
- Asks any remaining open questions inline.
- Explicitly asks the user to confirm or correct before you proceed.
Then STOP and wait for the user's reply. Do not generate files in the same turn as the recap, and do not proceed on the assumption that a fully-specified prompt implies consent to generate immediately — the recap catches misinterpretations of the prompt and is required even when questions #1–#10 are all pre-answered. The only way to skip the gate is if the user has already confirmed the recap earlier in this conversation.
What ships with it
20 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- evals/evals.json 15 KB
- references/AppTest.java 6.0 KB
- references/AvroConsumer.java 4.1 KB
- references/AvroProducer.java 5.2 KB
- references/AvroProducerSync.java 4.7 KB
- references/AvroShareConsumer.java 5.3 KB
- references/build.gradle 1.9 KB
- references/consumer.md 5.0 KB
- references/docker-compose.yml 690 B
- references/JsonSchemaConsumer.java 3.8 KB
- references/JsonSchemaProducer.java 4.6 KB
- references/KafkaConfig.java 7.6 KB
- references/multi-event-guide.md 3.7 KB
- references/pom.xml 4.6 KB
- references/readme-template.md 2.4 KB
- references/schema-generation-rules.md 3.1 KB
- references/share-consumer.md 4.9 KB
- references/value.avsc 1.1 KB
- references/value.schema.json 1.0 KB
- references/warpstream-optimization.md 7.8 KB
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 · 306 lines · 126 tokens per session scan A 3e714959e8a9
developing-kafka-java-client is a skill published in the GitHub repository confluentinc/agent-skills (54 stars, last pushed 4d ago), licensed Apache-2.0. It adds 126 tokens to every session and 7,184 once invoked, about $0.0006 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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