Agent skill
by giuseppe-trisciuoglio in giuseppe-trisciuoglio/developer-kit
Provides and generates LangChain4j tool and function calling patterns: annotates methods as tools with @Tool, configures tool executors, registers tools with AiServices, validates tool parameters…
$ npx skills add giuseppe-trisciuoglio/developer-kit --skill langchain4j-tool-function-calling-patterns -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install giuseppe-trisciuoglio/developer-kit langchain4j-tool-function-calling-patterns --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/giuseppe-trisciuoglio/developer-kit.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns .claude/skills/langchain4j-tool-function-calling-patterns && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "langchain4j-tool-function-calling-patterns" agent skill from https://github.com/giuseppe-trisciuoglio/developer-kit/tree/main/plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns into .claude/skills/langchain4j-tool-function-calling-patterns/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "langchain4j-tool-function-calling-patterns", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/giuseppe-trisciuoglio/developer-kit/tree/main/plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patternsType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add giuseppe-trisciuoglio/developer-kit --skill langchain4j-tool-function-calling-patterns -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install giuseppe-trisciuoglio/developer-kit langchain4j-tool-function-calling-patterns --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/giuseppe-trisciuoglio/developer-kit.git skills-src && mkdir -p .agents/skills && cp -r skills-src/plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns .agents/skills/langchain4j-tool-function-calling-patterns && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "langchain4j-tool-function-calling-patterns" agent skill from https://github.com/giuseppe-trisciuoglio/developer-kit/tree/main/plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns into .agents/skills/langchain4j-tool-function-calling-patterns/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "langchain4j-tool-function-calling-patterns", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add giuseppe-trisciuoglio/developer-kit --skill langchain4j-tool-function-calling-patterns -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install giuseppe-trisciuoglio/developer-kit langchain4j-tool-function-calling-patterns --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/giuseppe-trisciuoglio/developer-kit.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns .cursor/skills/langchain4j-tool-function-calling-patterns && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "langchain4j-tool-function-calling-patterns" agent skill from https://github.com/giuseppe-trisciuoglio/developer-kit/tree/main/plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns into .cursor/skills/langchain4j-tool-function-calling-patterns/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "langchain4j-tool-function-calling-patterns", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/giuseppe-trisciuoglio/developer-kit.git --path plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add giuseppe-trisciuoglio/developer-kit --skill langchain4j-tool-function-calling-patterns -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install giuseppe-trisciuoglio/developer-kit langchain4j-tool-function-calling-patterns --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/giuseppe-trisciuoglio/developer-kit.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns .gemini/skills/langchain4j-tool-function-calling-patterns && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "langchain4j-tool-function-calling-patterns" agent skill from https://github.com/giuseppe-trisciuoglio/developer-kit/tree/main/plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns into .gemini/skills/langchain4j-tool-function-calling-patterns/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "langchain4j-tool-function-calling-patterns", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install giuseppe-trisciuoglio/developer-kit langchain4j-tool-function-calling-patternsInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add giuseppe-trisciuoglio/developer-kit --skill langchain4j-tool-function-calling-patterns -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/giuseppe-trisciuoglio/developer-kit.git skills-src && mkdir -p .github/skills && cp -r skills-src/plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns .github/skills/langchain4j-tool-function-calling-patterns && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "langchain4j-tool-function-calling-patterns" agent skill from https://github.com/giuseppe-trisciuoglio/developer-kit/tree/main/plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns into .github/skills/langchain4j-tool-function-calling-patterns/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "langchain4j-tool-function-calling-patterns", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add giuseppe-trisciuoglio/developer-kit --skill langchain4j-tool-function-calling-patterns -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install giuseppe-trisciuoglio/developer-kit langchain4j-tool-function-calling-patterns --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/giuseppe-trisciuoglio/developer-kit.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns .opencode/skills/langchain4j-tool-function-calling-patterns && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "langchain4j-tool-function-calling-patterns" agent skill from https://github.com/giuseppe-trisciuoglio/developer-kit/tree/main/plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns into .opencode/skills/langchain4j-tool-function-calling-patterns/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "langchain4j-tool-function-calling-patterns", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
langchain4j-tool-function-calling-patternsProvides and generates LangChain4j tool and function calling patterns: annotates methods as tools with @Tool, configures tool executors, registers tools with AiServices, validates tool parameters…
Langchain4j Tool Function Calling Patterns is an agent skill from giuseppe-trisciuoglio/developer-kit. Provides and generates LangChain4j tool and function calling patterns: annotates methods as tools with @Tool, configures tool executors, registers tools with AiServices, validates tool parameters, and handles tool execution errors. Use when building AI agents that call tools, define function specifications, manage tool responses, or integrate external APIs with LLM-driven applications.
Its SKILL.md is about 2.4k tokens, which your agent loads only when the skill is triggered. The skill folder holds 9 other files, including reference files (for example `references/advanced-features.md`, `references/core-patterns.md` and `references/error-handling.md`).
It sits in AI & LLM Engineering, covering Structured output and tool calling and Building AI agents. The repository describes itself as: Modular plugin marketplace for Claude Code and agentic CLIs, with validated, spec-driven skills, agents, commands, and workflows for Java, TypeScript, Python, PHP, AWS, and AI. The licence is MIT.
5 steps, taken from the step headings in SKILL.md.
Read from SKILL.md and the folder at commit fe73fb3. It shows what the files ask for, not the result of running them.
Pre-approves these tools, so the agent can use them without asking each time:
ReadWriteEditBashGlobGrepWebFetchFrom allowed-tools in the SKILL.md frontmatter.
No scripts in the folder and no shell commands in SKILL.md (its code samples are java).
From the folder's file list and the shell code blocks in SKILL.md.
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Names these keys or tokens, usually read from environment variables:
API_KEYFrom names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Langchain4j Tool Function Calling Patterns loads about 2.4k tokens when it runs, and up to ~16k if it reads all its reference files. Until then it costs about 108 tokens; SKILL.md has 707 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
The automated check noted patterns worth knowing about, such as sudo or a known installer.
allowed-tools: Read, Write, Edit, Bash, Glob, Grep, WebFetchAutomated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
The full file from giuseppe-trisciuoglio/developer-kit at commit fe73fb3, republished under its MIT licence (© giuseppe-trisciuoglio). 707 words, ~2,363 tokens.
.claude/skills/langchain4j-tool-function-calling-patterns/SKILL.md (or your agent's skills folder). This skill also uses 8 other files; get the full folder from GitHub.Provides patterns for annotating methods as tools, configuring tool executors, registering tools with AI services, validating parameters, and handling tool execution errors in LangChain4j applications.
LangChain4j uses the @Tool annotation to expose Java methods as callable functions for AI agents. The AiServices builder registers tools with a chat model, enabling LLMs to perform actions beyond text generation: database queries, API calls, calculations, and business system integrations. Parameters use @P for descriptions that guide the LLM.
@Tool, @P annotations)AiServices.builder().tools()@ToolMemoryId@ToolDefine a tool class with methods annotated @Tool. Provide a description as the first parameter. Use @P for each parameter description.
public class WeatherTools {
private final WeatherService weatherService;
public WeatherTools(WeatherService weatherService) {
this.weatherService = weatherService;
}
@Tool("Get current weather for a city")
public String getWeather(
@P("City name") String city,
@P("Temperature unit: celsius or fahrenheit") String unit) {
return weatherService.getWeather(city, unit);
}
}Validate: Create an instance and confirm the class loads without errors.
Use AiServices.builder() to register tool instances with the chat model.
MathAssistant assistant = AiServices.builder(MathAssistant.class)
.chatModel(chatModel)
.tools(new Calculator(), new WeatherTools(weatherService))
.build();Validate: Call assistant.chat("What is 2 + 2?") and verify the LLM responds without throwing.
Send a prompt that triggers tool usage and verify the tool executes and its result is incorporated.
String response = assistant.chat("What is the weather in Rome?");
System.out.println(response);Validate: Check logs for tool invocation and confirm the response uses the tool output.
Add error handlers to gracefully manage failures without exposing stack traces.
AiServices.builder(Assistant.class)
.chatModel(chatModel)
.tools(new ExternalServiceTools())
.toolExecutionErrorHandler((request, exception) -> {
logger.error("Tool '{}' failed: {}", request.name(), exception.getMessage());
return "An error occurred while processing your request";
})
.hallucinatedToolNameStrategy(request ->
ToolExecutionResultMessage.from(request,
"Error: tool '" + request.name() + "' does not exist"))
.toolArgumentsErrorHandler((error, context) ->
ToolErrorHandlerResult.text("Invalid arguments: " + error.getMessage()))
.build();Validate: Trigger an error condition and confirm the LLM receives a safe error message.
Enable concurrent tool execution and set timeouts for long-running tools.
AiServices.builder(Assistant.class)
.chatModel(chatModel)
.tools(new DbTools(), new HttpTools())
.executeToolsConcurrently(Executors.newFixedThreadPool(5))
.toolExecutionTimeout(Duration.ofSeconds(30))
.build();Validate: Run concurrent requests and confirm no thread contention or deadlocks.
public class Calculator {
@Tool("Perform basic arithmetic")
public double calculate(
@P("Expression like 2+2 or 10*5") String expression) {
// Parse and evaluate expression
return eval(expression);
}
}
Assistant assistant = AiServices.builder(Assistant.class)
.chatModel(ChatModel.builder()
.apiKey(System.getenv("API_KEY"))
.model("gpt-4o")
.build())
.tools(new Calculator())
.build();@Tool(value = "Send email notification", returnBehavior = ReturnBehavior.IMMEDIATELY)
public void sendEmail(@P("Recipient email address") String to,
@P("Email subject") String subject,
@P("Email body") String body) {
emailService.send(to, subject, body);
}ToolProvider provider = request -> {
if (request.userContext().contains("admin")) {
return List.of(new AdminTools());
}
return List.of(new UserTools());
};
AiServices.builder(Assistant.class)
.chatModel(chatModel)
.toolProvider(provider)
.build();@Tool names: Use imperative verbs ("Get", "Send", "Calculate") with clear scope@P descriptions: Include format, constraints, and valid values — vague descriptions cause incorrect LLM calls.toolExecutionTimeout() for external service calls.executeToolsConcurrently() when tools are independent| Issue | Solution |
|---|---|
| LLM calls non-existent tool | Add .hallucinatedToolNameStrategy() returning a safe error message |
| Tools receive wrong parameters | Refine @P descriptions; add .toolArgumentsErrorHandler() |
| Tool execution hangs | Set .toolExecutionTimeout(Duration.ofSeconds(N)) |
| Rate limit errors from external API | Add retry logic or rate limiter inside the tool method |
| LLM ignores tool output | Ensure the tool returns a string the LLM can interpret |
See references/error-handling.md for resilience patterns and references/core-patterns.md for parameter and return type details.
| Annotation / API | Purpose |
|---|---|
@Tool | Marks a method as a callable tool |
@P | Describes a tool parameter for the LLM |
@ToolMemoryId | Injects conversation/user ID into the tool |
AiServices.builder() | Creates AI service with registered tools |
ReturnBehavior.IMMEDIATELY | Execute tool without waiting for LLM response |
ToolProvider | Dynamic tool provisioning based on context |
executeToolsConcurrently() | Run independent tool calls in parallel |
toolExecutionTimeout() | Timeout for individual tool calls |
@Tool or @P descriptionsToolProvider for conditional registration@P descriptions directly cause incorrect tool calls — be specific about formats and constraintsexecuteToolsConcurrently()langchain4j-ai-services-patterns — High-level AI service configurationlangchain4j-rag-implementation-patterns — RAG retrieval with tool integrationlangchain4j-spring-boot-integration — Tool registration in Spring Boot applications© giuseppe-trisciuoglio, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
SKILL.md and 8 other files (references) in plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns of giuseppe-trisciuoglio/developer-kit.
Open the folder on GitHubat commit fe73fb3
Langchain4j Tool Function Calling Patterns next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Langchain4j Tool Function Calling Patterns this skillgiuseppe-trisciuoglio/developer-kit | 356 | — | ~2.4k | Automated safety check: Notes | MIT | |
| Google Agents CLI Adk Codepifferologo/cloud-agents-cli | 129 | 1 repos | ~768 | Automated safety check: Pass | Apache-2.0 | |
| E2b Code Interpreteragent-sandbox/agent-sandbox | 218 | — | ~2.3k | Automated safety check: Pass | Apache-2.0 | |
| Output Dev Agent Classgrowthxai/output | 442 | — | ~2.6k | Automated safety check: Pass | Apache-2.0 | |
| Agents And MiddlewareVectorSpaceLab/AREX-Skill | 330 | — | ~1.2k | Automated safety check: Pass | MIT | |
| Build Agentsvercel/vercel-plugin | 301 | — | ~1.4k | Automated safety check: Pass | Custom licence |
pifferologo/cloud-agents-cli
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agent-sandbox/agent-sandbox
Execute code in E2B sandboxes and integrate with LLMs for tool calling.
growthxai/output
Use the Agent class for multi-step tool loops, conversation history, streaming progress, and reusable LLM agents.
VectorSpaceLab/AREX-Skill
Work on the actively maintained LangChain v1 agent package: initchatmodel, createagent, structured output, tools, middleware, embeddings initialization, provider routing, and agent runtime…
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Posts review findings from a JSON file as inline comments on a GitHub Pull Request, attaching each comment to its file and line.
Categories
Provides and generates LangChain4j tool and function calling patterns: annotates methods as tools with @Tool, configures tool executors, registers tools with AiServices, validates tool parameters…. Langchain4j Tool Function Calling Patterns is an agent skill from giuseppe-trisciuoglio/developer-kit. Provides and generates LangChain4j tool and function calling patterns: annotates methods as tools with @Tool, configures tool executors, registers tools with AiServices, validates tool parameters, and handles tool execution errors.
Langchain4j Tool Function Calling Patterns fits situations like: building AI agents that call tools; define function specifications; manage tool responses; integrate external APIs with LLM-driven applications.
Run `npx skills add giuseppe-trisciuoglio/developer-kit --skill langchain4j-tool-function-calling-patterns -a claude-code`. Or copy the skill folder (plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns in giuseppe-trisciuoglio/developer-kit) into .claude/skills/langchain4j-tool-function-calling-patterns in your project. Claude Code loads it when a task matches its description.
Run `npx skills add giuseppe-trisciuoglio/developer-kit --skill langchain4j-tool-function-calling-patterns -a codex`. Or copy the skill folder (plugins/developer-kit-java/skills/langchain4j-tool-function-calling-patterns in giuseppe-trisciuoglio/developer-kit) into .agents/skills/langchain4j-tool-function-calling-patterns in your project. Codex loads it when a task matches its description.
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add giuseppe-trisciuoglio/developer-kit --skill langchain4j-tool-function-calling-patterns -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/langchain4j-tool-function-calling-patterns, .gemini/skills/langchain4j-tool-function-calling-patterns, .github/skills/langchain4j-tool-function-calling-patterns and .opencode/skills/langchain4j-tool-function-calling-patterns in your project.
Going by SKILL.md and its folder, Langchain4j Tool Function Calling Patterns needs credentials named API_KEY. Our summary lists: A credential in API_KEY. Its frontmatter pre-approves these tools: Read, Write, Edit, Bash, Glob, Grep, WebFetch.
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Our automated static check of SKILL.md found notes only (pre-approves every shell command (allowed-tools: bash)), nothing it rates as a warning. It is not a guarantee. Review the folder before installing.
Langchain4j Tool Function Calling Patterns is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
About 2.4k tokens (SKILL.md is roughly 9.5k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 14k tokens, read only when the agent opens those files.
Skills that share tags, products or a category with Langchain4j Tool Function Calling Patterns: Google Agents CLI Adk Code (pifferologo/cloud-agents-cli, 129 stars), E2b Code Interpreter (agent-sandbox/agent-sandbox, 218 stars), Output Dev Agent Class (growthxai/output, 442 stars) and Agents And Middleware (VectorSpaceLab/AREX-Skill, 330 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
giuseppe-trisciuoglio (a GitHub user) maintains it in giuseppe-trisciuoglio/developer-kit, which has 356 GitHub stars. The repository holds 115 skills in this directory. The repository was last updated on September 10, 2026.
Source: giuseppe-trisciuoglio/developer-kit on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.
