AI-500 key terms
AI-500 · Get comfortable with the vocabulary.
- Agent
- Related: Orchestrator Agent, Tool Calling, Agent Identity
A software component that uses a language model to reason about a goal, decide on actions, call tools, and produce results with some autonomy rather than only answering a single prompt.
- Orchestrator Agent
- Related: Agent, Handoff, Multi-Agent Pattern
A coordinating agent that decomposes a request, decides which specialist agents or tools to invoke, passes context between them, and assembles the final response for the user.
- Subagent
- Related: Orchestrator Agent, Agent Role, Handoff
A narrower agent invoked by a parent or orchestrator agent to handle one bounded task, usually with a smaller tool set and its own instructions and context.
- Multi-Agent Pattern
- Related: Orchestrator Agent, Handoff, Group Chat
A recurring structural design for splitting work among several agents, such as supervisor, sequential pipeline, concurrent fan-out, or debate, chosen to match task dependencies and failure tolerance.
- Handoff
- Related: Orchestrator Agent, Shared State, Agent Role
Transferring control of a conversation or task from one agent to another, along with the context the receiving agent needs to continue without asking the user to repeat information.
- Agent Role
- Related: Subagent, Agent Instructions, Handoff
The declared responsibility, scope, and boundaries assigned to an agent, which shapes its instructions, allowed tools, and what it is permitted to decide or escalate.
- Agent Instructions
- Related: Agent Role, Tool Calling, Guardrail
The system-level prompt text that defines an agent's persona, goals, constraints, output format, and escalation rules, and that is applied on every turn of its reasoning.
- Tool Calling
- Related: Agent, Function Schema, Agent Instructions
The mechanism by which a model emits a structured request for an external function, such as an API or database lookup, whose result is returned to the model for further reasoning.
- Function Schema
- Related: Tool Calling, Agent Instructions
The machine-readable description of a callable tool, covering its name, purpose, parameter types, and required fields, that the model uses to decide when and how to call it.
- Shared State
- Related: Handoff, Conversation Thread, Checkpointing
A common store of conversation history, intermediate results, and task status that multiple agents read and update so their work stays consistent across handoffs.
- Conversation Thread
- Related: Shared State, Checkpointing, Context Window
An ordered record of messages and tool interactions belonging to one session, used to preserve context and to let agents resume or audit a multi-turn exchange.
- Context Window
- Related: Conversation Thread, Context Engineering, Token Budget
The maximum amount of text, in tokens, that a model can consider at once; managing it is essential because multi-agent transcripts grow quickly and can exceed the limit.
- Context Engineering
- Related: Context Window, Token Budget, Shared State
Deliberately selecting, summarizing, and ordering what each agent sees, so it receives relevant state and instructions without flooding the model with unnecessary history.
- Token Budget
- Related: Context Window, Context Engineering, Cost per Task
A planned cap on tokens consumed per request, agent, or workflow, used to control cost and latency and to force summarization before limits are reached.
- Checkpointing
- Related: Shared State, Conversation Thread, Idempotency
Persisting an agent workflow's progress at defined points so a long-running or failed run can resume from the last good state instead of restarting from the beginning.
- Idempotency
- Related: Checkpointing, Tool Calling, Retry Policy
A property of an operation that produces the same result when repeated, which lets agents safely retry tool calls after timeouts without duplicating side effects like orders or payments.
- Retry Policy
- Related: Idempotency, Circuit Breaker, Observability
Rules governing automatic re-attempts of failed calls, including which errors are retryable, how many attempts are allowed, and how long to wait between them.
- Circuit Breaker
- Related: Retry Policy, Observability
A protective pattern that stops sending requests to a failing dependency after repeated errors, failing fast until a recovery period passes, to prevent cascading agent failures.
- Group Chat
- Related: Multi-Agent Pattern, Shared State, Handoff
A coordination style in which several agents exchange messages in one shared conversation, with a manager or rule deciding who speaks next and when to stop.
- Agent Framework
- Related: Orchestrator Agent, Tool Calling, Shared State
A software library or service that supplies the plumbing for agents, including model clients, tool registration, message passing, state management, and orchestration primitives.
- Model Deployment
- Related: Agent Framework, Provisioned Throughput, Content Filter
A provisioned hosting endpoint for a language model in a cloud environment, with a chosen model version, capacity, and region that agents call at runtime.
- Grounding
- Related: Retrieval-Augmented Generation, Tool Calling, Hallucination
Supplying an agent with authoritative external data, such as documents or search results, so its answers rest on retrieved facts rather than only on model training.
- Retrieval-Augmented Generation
- Related: Grounding, Vector Index, Hallucination
A technique that retrieves relevant content from a knowledge source and inserts it into the model's context before generation, improving factual accuracy and traceability.
- Vector Index
- Related: Retrieval-Augmented Generation, Grounding
A data structure storing embedded representations of content so that semantically similar items can be found quickly during retrieval for grounding an agent's response.
- Hallucination
- Related: Grounding, Evaluator Agent, Guardrail
A confident model output that is fabricated or unsupported by available evidence, which multi-agent designs mitigate through grounding, verification agents, and explicit refusal instructions.
- Evaluator Agent
- Related: Hallucination, LLM-as-Judge, Evaluation Dataset
An agent whose job is to judge another agent's output against criteria such as accuracy, completeness, or policy compliance, producing a score or corrective feedback.
- LLM-as-Judge
- Related: Evaluator Agent, Evaluation Dataset, Regression Testing
Using a language model to score or compare outputs against a rubric, which scales qualitative evaluation but requires calibration against human-labeled examples.
- Evaluation Dataset
- Related: LLM-as-Judge, Regression Testing, Golden Response
A curated set of representative inputs with expected outputs or grading criteria, used to measure agent quality consistently and to compare changes over time.
- Golden Response
- Related: Evaluation Dataset, Regression Testing
A human-approved reference answer for a test case that serves as the benchmark against which an agent's output is compared during evaluation.
- Regression Testing
- Related: Evaluation Dataset, LLM-as-Judge, Continuous Evaluation
Re-running a fixed evaluation suite after changes to prompts, models, or tools to detect quality drops before the updated solution reaches production.
- Continuous Evaluation
- Related: Regression Testing, Observability, Telemetry
Ongoing automated scoring of live or sampled production interactions so quality drift, new failure modes, and unsafe outputs are detected between formal release cycles.
- Observability
- Related: Distributed Tracing, Telemetry, Continuous Evaluation
The ability to understand an agent system's internal behavior from its outputs, achieved through traces, logs, and metrics that show each step of a multi-agent run.
- Distributed Tracing
- Related: Observability, Telemetry, Token Usage
Recording a single request's path across agents, tools, and services as linked spans, so latency and errors can be attributed to a specific step.
- Telemetry
- Related: Observability, Distributed Tracing, Token Usage
The metrics, logs, and events emitted by a running system and collected centrally, used to monitor health, cost, and behavior of agents in production.
- Token Usage
- Related: Token Budget, Cost per Task, Telemetry
The count of input and output tokens consumed by model calls, tracked per agent and per request because it drives both cost and latency in multi-agent workflows.
- Cost per Task
- Related: Token Usage, Token Budget
The total model and tool spend divided by successfully completed tasks, a business-level metric for judging whether a multi-agent design is economically viable.
- Agent Identity
- Related: Managed Identity, Least Privilege, Tool Calling
The authenticated identity an agent uses to access resources, ideally distinct from a human user's credentials, so permissions can be scoped and audited per agent.
- Managed Identity
- Related: Agent Identity, Least Privilege, Secret Management
A platform-issued identity for a hosted workload that obtains tokens automatically, removing the need to store secrets in code or configuration for agent-to-service calls.
- Least Privilege
- Related: Agent Identity, Managed Identity, Guardrail
Granting each agent and identity only the permissions its task requires, limiting the blast radius if a prompt injection or bug causes unintended tool calls.
- Guardrail
- Related: Content Filter, Prompt Injection, Human in the Loop
A control that constrains agent behavior, such as input filtering, output validation, allowed-tool lists, or human approval, to keep actions within policy and safety bounds.
- Content Filter
- Related: Guardrail, Prompt Injection
A service-side classifier that screens model inputs and outputs for harmful categories and can block or annotate them before they reach users or downstream agents.
- Prompt Injection
- Related: Guardrail, Least Privilege, Human in the Loop
An attack that hides malicious instructions in content an agent processes, attempting to override its instructions or trigger unauthorized tool calls and data exposure.
- Human in the Loop
- Related: Guardrail, Prompt Injection
A design in which a person reviews or approves an agent's proposed action before it executes, used for high-impact operations that should not run fully autonomously.
- Secret Management
- Related: Managed Identity, Agent Identity
Storing and rotating credentials such as API keys in a protected vault rather than in code or prompts, so agents can authenticate without exposing sensitive values.
- Provisioned Throughput
- Related: Model Deployment, Token Usage
A reserved model capacity model that guarantees a fixed processing rate for predictable latency and cost, in contrast to pay-per-token consumption-based deployment.
- Responsible AI Review
- Related: Guardrail, Content Filter, Human in the Loop
A structured assessment of an agent solution for fairness, safety, transparency, and privacy risks before deployment, with mitigations documented and tracked.