# Agent The Agent block connects your workflow to Large Language Models (LLMs). It processes natural language inputs, calls external tools, and generates structured or unstructured outputs. ![Agent Block Configuration](https://docs.steelengine.com/static/blocks/agent.png) ## Configuration Options ### Messages The Messages field holds the conversation the model receives. It is an ordered list of messages, each with a role (`system`, `user`, or `assistant`) and content. System messages establish the agent's role, response methodology, and processing boundaries. User and assistant messages form the conversation the model continues. A new block starts with one empty user message. ```json [ { "role": "system", "content": "You are a helpful assistant that specializes in financial analysis. Always provide clear explanations and cite sources when possible. When responding to questions about investments, include risk disclaimers." }, { "role": "user", "content": "" } ] ``` Reference upstream data inside any message with the `` syntax, for example `` or ``. If you add several system messages, SteelEngine joins them into one set of instructions. Use the AI wand on the field to generate or revise the whole message list from a description. ### Model Type or select a model in the model combobox. The list covers OpenAI, Anthropic, Google, Vertex AI, Azure OpenAI, Azure Anthropic, AWS Bedrock, xAI, Deepseek, Groq, Cerebras, Mistral AI, Kimi, Fireworks, and OpenRouter, plus local models served by Ollama or a VLLM compatible endpoint. Model IDs use the vendor's spelling, for example `gpt-5.4`, `claude-sonnet-4-6`, or `gemini-2.5-pro`. Hosted-provider variants carry a prefix such as `azure/`, `vertex/`, or `bedrock/`. Which advanced settings appear (Temperature, Reasoning Effort, Verbosity, Thinking Level) depends on the model you pick. ### API Key Your API key for the selected LLM provider. This is securely stored and used for authentication. ### Provider Credentials Some providers need more than a key. These fields appear only when you select a matching model: * **Azure Endpoint** and **Azure API Version**: for `azure/` and `azure-anthropic/` models * **Google Cloud Account**, **Vertex AI Project**, and **Vertex AI Location**: for `vertex/` models. Connect a Google Cloud account with OAuth, or enter a credential ID under **Advanced** * **AWS Access Key ID**, **AWS Secret Access Key**, and **AWS Region**: for `bedrock/` models ### Temperature An **Advanced** slider that controls response randomness and creativity. The range depends on the model. Most providers accept 0-2, and Anthropic models accept 0-1. The slider is hidden for models that do not support temperature. * **Low (0-0.3)**: Deterministic and focused. Best for factual tasks and accuracy. * **Medium (0.3-0.7)**: Balanced creativity and focus. Good for general use. * **High (0.7 up to the model's maximum)**: Creative and varied. Ideal for brainstorming and content generation. ### Reasoning Effort, Verbosity, and Thinking Level Three **Advanced** selects for models with extended reasoning. **Reasoning Effort** (`auto`, `low`, `medium`, `high`) and **Verbosity** (`auto`, `low`, `medium`, `high`) apply to OpenAI reasoning models. **Thinking Level** (`none`, `minimal`, `low`, `medium`, `high`, `max`) applies to Anthropic and Gemini models with thinking. Each select offers only the options the selected model supports. ### Max Output Tokens Controls the maximum length of the model's response. Each model defaults to its full max output token limit (e.g., 64,000 tokens for Claude Sonnet 4.5). You can override this with a custom value using the **Max Output Tokens** setting under **Advanced**. For Anthropic models, when non-streaming requests exceed the SDK's internal threshold, the provider automatically uses internal streaming to avoid timeouts. ### Tools Extend agent capabilities with external integrations. Select any integration tool from the toolbar, add tools from a connected MCP server, or define custom functions. **Example Categories:** * **Communication**: Gmail, Slack, Telegram, WhatsApp, Microsoft Teams * **Data Sources**: Notion, Google Sheets, Airtable, Supabase, Pinecone * **Web Services**: Firecrawl, Google Search, Exa AI, browser automation * **Development**: GitHub, Jira, Linear * **AI Services**: OpenAI, Perplexity, Hugging Face, ElevenLabs **Usage Control:** each tool has a usage setting, shown as a small label on the tool row. * **Auto**: Model decides when to use the tool based on context * **Force**: Tool must be called in every request * **None**: SteelEngine removes the tool before it sends the request to the model — effectively disables the tool without deleting it ### Skills Attach [Agent Skills](/skills) from your workspace. The agent's instructions gain a list of the attached skills with their descriptions, and the model receives a `load_skill` tool. When the model decides a skill is relevant, it calls `load_skill` and receives the skill's full instructions. Skills load on demand, so attaching several does not bloat every request. ### Memory Memory lets the agent remember earlier turns across runs without a separate block. * **None**: Each run is independent * **Conversation**: The full history for the conversation, trimmed to fit the model's context window * **Sliding window (messages)**: The most recent N messages. Set N in **Sliding Window Size** (default 10) * **Sliding window (tokens)**: The most recent messages that fit a token budget. Set the budget in **Max Tokens** (default 4,000) Any mode other than None requires a **Conversation ID**, for example `user-123` or a reference to an upstream field. Runs that share a Conversation ID share a history. On the first run for an ID, the user and assistant messages in Messages seed the history. On later runs, the block loads the stored history and appends the latest user message from Messages. System messages are never stored. ### Response Format The Response Format parameter enforces structured output generation through JSON Schema validation. This ensures consistent, machine-readable responses that conform to predefined data structures: ```json { "name": "user_analysis", "schema": { "type": "object", "properties": { "sentiment": { "type": "string", "enum": ["positive", "negative", "neutral"] }, "confidence": { "type": "number", "minimum": 0, "maximum": 1 } }, "required": ["sentiment", "confidence"] } } ``` This configuration constrains the model's output to comply with the specified schema, preventing free-form text responses and ensuring structured data generation. ### Previous Interaction ID Shown only for the Google `deep-research-pro-preview-12-2025` model (and its `vertex/` variant). Pass the `interactionId` output of an earlier Agent block to continue that research session. This model does not expose Tools, Skills, Memory, Response Format, or Max Output Tokens. ### Accessing Results After an agent completes, you can access its outputs: * **``**: The agent's response text or structured data * **``**: Token usage statistics (`input`, `output`, `total`) * **``**: Tool execution details (`list`, `count`) * **``**: Provider and tool execution timing details * **``**: Estimated cost of the API call (`input`, `output`, `toolCost`, `total`, `pricing`), if available * **``**: Provider interaction identifier, when the provider returns one ## Advanced Features ### Memory + Agent: Conversation History Set **Memory** on the Agent block to a mode other than None and give it a **Conversation ID** (see [Memory](#memory) above). The block loads the stored history before each request and appends the new turn after it. Chat-style workflows need no extra blocks. For history you want to read or write from other blocks, or to share between agents, use the [`Memory`](/tools/memory) block with a consistent `id` and reference its output in Messages. ### Model Availability Organization admins can disable models in the **Model availability** section of the organization settings, and workspace settings can disable more for one workspace. The Agent block checks the selected model against these restrictions before every run. A run that names a disabled model fails at that block. ## Outputs * **``**: Agent's response text * **``**: Model identifier used for the request * **``**: Token usage statistics (`input`, `output`, `total`) * **``**: Tool execution details (`list`, `count`) * **``**: Provider and tool execution timing details * **``**: Estimated API call cost (`input`, `output`, `toolCost`, `total`, `pricing`) * **``**: Provider interaction identifier, when available ## Example Use Cases **Customer Support Automation** - Handle inquiries with database and tool access ``` API (Ticket) → Agent (Postgres, KB, Linear) → Gmail (Reply) → Memory (Save) ``` **Multi-Model Content Analysis** - Analyze content with different AI models ``` Function (Process) → Agent (GPT-4o Technical) → Agent (Claude Sentiment) → Function (Report) ``` **Tool-Powered Research Assistant** - Research with web search and document access ``` Input → Agent (Google Search, Notion) → Function (Compile Report) ``` ## Best Practices * **Be specific in system messages**: Clearly define the agent's role, tone, and limitations. The more specific your instructions are, the better the agent will be able to fulfill its intended purpose. * **Choose the right temperature setting**: Use lower temperature settings (0-0.3) when accuracy is important, or increase temperature toward the model's maximum for more creative or varied responses * **Leverage tools effectively**: Integrate tools that complement the agent's purpose and enhance its capabilities. Be selective about which tools you provide to avoid overwhelming the agent. For tasks with little overlap, use another Agent block for the best results. ## Common Questions **What LLM providers does the Agent block support?** The Agent block supports OpenAI, Anthropic, Google (Gemini), Vertex AI, Azure OpenAI, Azure Anthropic, AWS Bedrock, xAI (Grok), DeepSeek, Groq, Cerebras, Mistral AI, Kimi (Moonshot), Fireworks, OpenRouter, and local models via Ollama or VLLM. You can type or select any supported model from the model combobox. **What are the memory options for the Agent block?** The Agent block has four memory modes: None (no memory, each request is independent), Conversation (full conversation history keyed by a conversation ID, trimmed to the model's context window), Sliding Window by messages (keeps the N most recent messages, 10 by default), and Sliding Window by tokens (keeps messages up to a token limit, 4,000 by default). Memory requires a conversation ID to persist across runs. **What is the difference between the tool usage modes (Auto, Force, None)?** In Auto mode, the model decides when to call a tool based on context. In Force mode, the model must call the tool on every request. In None mode, the tool is removed before the request and never sent to the model — it effectively disables that tool without removing it from the configuration. **How does the Response Format work?** Response Format enforces structured output by providing a JSON Schema. When set, the model's response is constrained to match the schema exactly. Fields from the structured response can be accessed directly by downstream blocks using syntax. If no response format is set, the agent returns its standard content and model outputs. The tokens, toolCalls, providerTiming, cost, and interactionId outputs are returned in both cases. **What do the Reasoning Effort, Verbosity, and Thinking Level settings do?** These are advanced settings that appear only for models that support extended reasoning. Reasoning Effort and Verbosity apply to OpenAI o-series, GPT-5, and GPT-6 models. Thinking Level applies to Anthropic Claude and Gemini models with thinking. They control how much compute the model spends reasoning before responding and how long its answers run. Higher levels produce more thorough answers but cost more tokens and take longer. **How does max output tokens work with Anthropic models specifically?** The Agent block uses each Anthropic model's full max output token limit by default (e.g., 64,000 for Claude Sonnet 4.5). You can override this with the Max Output Tokens setting. For non-streaming requests that exceed the SDK's internal threshold, the provider automatically uses internal streaming to avoid timeouts. **Can I use the Agent block with a custom or self-hosted model?** Yes. You can use any Ollama or VLLM-compatible model by typing the model name directly into the model combobox. This lets you connect to locally hosted or custom-deployed models as long as they expose a compatible API endpoint.