Custom AI Agent Glossary
The words that come up when you evaluate custom AI agents, defined plainly, each with its source. Start with agent, workflow and human-in-the-loop; the field guide puts them in context.
- Agent (AI agent)
A system that uses a language model to carry out a task on someone's behalf: it decides its next step, uses tools to read data and take actions, and stops or hands back to a person when it should. Anthropic distinguishes agents, where the model directs its own process, from workflows, where the steps are fixed in code.[1][2]
- Agent washing
Gartner's term for rebranding existing assistants, robotic process automation or chatbots as agents without real agentic capability.[3]
- Baseline
The measured performance of a workflow before the agent: time, cost, volume and error rate. Without one, a return can't be shown.[3]
- Chatbot
Software that answers questions in a conversation. The user drives every turn, and it rarely takes actions in other systems.
- Copilot
An AI assistant built into a product that helps a person while they work, by drafting, suggesting or summarizing. The person decides each step and finishes the work.[4]
- Custom AI agent
An agent built for one organization's workflow, working inside its systems and under its controls, as opposed to a ready-made product sold to every customer. The model is usually commercial; the instructions, tools, integrations, guardrails and tests are custom.[1]
- Evaluation (evals)
Testing an agent or model on a set of cases and scoring the results, automatically where answers are checkable and by expert review where they are not.[5][1]
- Excessive agency
Giving an agent more permissions, tools or autonomy than its job needs, so a mistake or attack can do more damage. Named in OWASP's Top 10 for LLM applications.[6]
- Ground truth
The known right answer for a test case, used to score an agent's output objectively. Benchmarks such as BORE rank models only on exact checks against ground truth.[5]
- Guardrails
Checks around an agent that keep it within bounds: validating inputs, screening for unsafe or off-topic requests, limiting which tools and actions it may use, and checking outputs before they are used.[1]
- Hallucination
Output from a language model that sounds plausible but is false, such as an invented citation. The reason outputs that matter need verification.[7]
- Human-in-the-loop
A design where a person reviews, approves or can override an agent's work at set points, typically before irreversible or high-risk actions and when the agent repeatedly fails. Some regulations require human oversight for high-risk uses.[1][8]
- Instructions (system prompt)
The written guidance that defines what an agent does and how: its steps, rules, tone and when to escalate. Good instructions are often drawn from an organization's existing procedures.[1]
- Model Context Protocol (MCP)
An open standard for connecting AI applications to external tools and data sources in a consistent way.[9]
- Multi-agent system
Several agents working together, each with its own instructions and tools, coordinated by a manager agent or by hand-offs between them. OpenAI recommends starting with one agent and splitting only when it becomes hard to manage.[1]
- Orchestration
How an agent system sequences its steps, tools and models: a fixed chain, routing to specialized handlers, parallel work, or an orchestrator model that hands subtasks to worker models and combines their results.[2][1]
- Pilot
A limited trial of an agent, often on selected cases. A pilot shows feasibility; only results on live volume over time show a production return.[3]
- Production readiness
The point at which an agent can run on live volume without rescue: tested against real cases with known answers, permissions limited to what it needs, oversight and logging in place, monitoring running, and an owner named to maintain it.[10][6]
- Prompt injection
An attack where instructions hidden in content the agent reads, such as a document, web page or email, try to change what it does. OWASP ranks it first among risks to LLM applications.[6]
- Shadow mode
Running an agent alongside the existing process without using its output, so people can compare its work with their own before trusting it.
- Tools (function calling)
The functions an agent can call to read data or take actions, such as searching a database, updating a record or sending a message. OpenAI's guide lists tools with the model and instructions as an agent's three core parts.[1]
- Workflow
A repeatable sequence of steps that turns a trigger into a finished output, such as an inbound document into a filed record. In Anthropic's usage, an LLM workflow follows predefined code paths, unlike an agent that chooses its own steps.[2]
Sources
- A practical guide to building agents · OpenAI, 2025
- Building effective agents · Anthropic, December 2024
- Gartner Predicts Over 40% of Agentic AI Projects Will Be Canceled by End of 2027 · Gartner (press release), June 25, 2025
- Microsoft Copilot Studio documentation · Microsoft Learn
- BORE: Business Operations Real Eval · Eigenomic
- OWASP Top 10 for LLM Applications · OWASP GenAI Security Project
- Formal Opinion 512: Generative Artificial Intelligence Tools · American Bar Association Standing Committee on Ethics and Professional Responsibility, July 29, 2024
- The EU Artificial Intelligence Act · artificialintelligenceact.eu
- Model Context Protocol · modelcontextprotocol.io
- AI Risk Management Framework · U.S. National Institute of Standards and Technology (NIST)
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