> For the complete documentation index, see [llms.txt](https://docs.stackai.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.stackai.com/technical-reference/core-concepts/agents-workflows-nodes-tools-and-skills.md). # Agents, Workflows, Nodes, Tools, and Skills Agents use instructions and available tools to respond to requests. Workflows connect explicit processing steps. Skills package reusable instructions and resources so you can apply the same procedure in more than one agent. {% embed url="" %} Locate agent instructions, skills, and tools within a connected workflow. {% endembed %} ## Before you begin Permission to edit a project and access to any required connections. ## Agents, workflows, and reusable components | Term | Definition | | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | Agent | A model-driven process that uses instructions, context, and available tools to respond to a request. The model chooses whether and how to call the tools made available to it. | | Workflow | Connected processing steps with explicit input, output, and dependency relationships. Use connections and routing to control the processing path. | | Node | A configured processing, input, output, or control step in a workflow. Inspect its inputs and result independently when tracing a problem. | | Tool | An operation that an agent or workflow can call. Its input schema and permissions determine what the caller can supply and do. | | Skill | Reusable instructions and supporting resources that guide an agent through a task. It supplies guidance, not provider credentials or additional permissions. | ## Choose between agents and workflows 1. Choose an agent for model-directed tool use or a workflow for an explicit sequence. 2. Add only the tools needed for the task. Supply instructions that explain when to use them. 3. Attach a skill when the same instructions or resources must be reused. The project has a defined task, the required operations, and reusable guidance where appropriate. ## Behavior and limitations A tool exposes an operation; it does not tell the agent when that operation is appropriate. A skill does not grant access to a provider account. Each action still needs valid inputs, connections, and permissions. ## Related resources [Organizations, Workspaces, Folders, and Projects](/technical-reference/core-concepts/organizations-workspaces-folders-and-projects.md) --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.stackai.com/technical-reference/core-concepts/agents-workflows-nodes-tools-and-skills.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.