# Choosing — I want X, so use Y, not Z, because > Seven tables for the choices that come up in every app with agents in it: an agent or a plain model call or a workflow step; alone, propose, or a standing rule; an assignment or a process; one agent with more tools or delegation; a queue or a person for approvals; when each Privacy kit arrives; and how to test without a model. Each row says what to use, what not to, and why. > **You are here:** [Building with agents](https://osysharp.com/reference/agent/guide/) › Choosing ## Summary {#summary} Find the row that says what you want. Each one names what to use, what to leave, and the reason in a sentence. Every "use" is a link to the page that shows it working. ## Description {#description} ### Do I need an agent, a model call, or a workflow step? {#agent-or-call} | I want | Use | Not | Because | |---|---|---|---| | one answer from a model: a summary, a draft, a translation | [[agent-llm-calls\|`Llm.Complete`]] | an agent | nothing has to be looked up or changed, so there is nothing for an agent's account, gate or record to do. The call is still routed, limited and metered. | | fields read out of a text, or one decision among a few | [[agent-llm-typed-answers\|`Llm.Extract` · `Llm.Decide`]] | an agent | the answer is typed and checked against its class already | | the model to look things up in my app, or change something in it | an [[agent-agents\|agent]] with a [[agent-skills\|skill]] | a model call with my own loop around it | tools then run as an account with rights, under a gate, within a limit, on a record | | the same steps every time, with no judgement in them | a plain function or a [[workflow-index\|workflow]] | an agent | it is cheaper, exact, and needs no model | | steps over several days, with people between them, and judgement in one or two of them | a workflow with an [[agent-processes\|agent step]] | one long agent job | the process owns the order and the waiting; the agent does only the step that needs judgement | | a conversation with a person | [[agent-ask#ask\|`Ask` or `Stream`]] on an agent | `Do` | the answer is words, not a typed result | ### Should it act alone, propose, or get a standing rule? {#alone-or-propose} | The tool | Use | Not | Because | |---|---|---|---| | only reads | nothing: it runs alone | — | a tool marked `Query` is never proposed | | changes the app's own data, and a person reads the result anyway | `Alone`, or [[agent-autonomy#gate\|`Permits.ChangesAlone()`]] | proposing each one | an approval nobody ever refuses teaches people to press yes | | sends something, spends money, or reaches outside the app | [[agent-autonomy#proposal\|propose]] — the default | `Permits.Everything()` | it cannot be taken back, and a person's yes runs it with that person's rights | | must be seen by a person every single time | `ProposeEveryTime` | a standing rule | a tool listed there takes no "from now on, alone" | | must never be done by this agent | `Never` | trusting the instructions | the tool is not offered to the model at all, and cannot be approved | | is approved again and again by the same person | a [[agent-autonomy#standing\|standing rule]] | changing the code | it covers only the work done for the person who gave it, counts its own use, and can be taken back | | belongs to another department | a skill's [[agent-autonomy#route\|`DecidedBy`]], to a restricted queue | the default | the person who asked then cannot approve it themselves | ### Is this an assignment or a process? {#assignment-or-process} | The work | Use | Not | Because | |---|---|---|---| | has the same steps each time, known in advance | a [[agent-processes\|process]] | an assignment | the steps are the point: they can be drawn, timed and followed | | has a known outcome and an unknown way there | an [[agent-assignments\|assignment]] | a process | it is done when its criteria are met, not when everything attached to it has finished | | may come back after it was closed | an [[agent-assignments#reopen\|assignment]] | a new process run | it reopens and keeps everything it had | | is one question or one approval | a [[agent-human-requests\|request]] | either | a request is answered once and is done | | gathers evidence, letters and findings as it goes | an assignment with a [[agent-work-repositories\|work repository]] | lines in a log | each item keeps who added it, from where, and every version | The two combine. An assignment can have agent work, requests and a process attached to it; any of them can fail or be replaced and the assignment stays. See [[agent-assignments#work]]. ### One agent with more tools, or delegation? {#tools-or-delegation} | The job | Use | Not | Because | |---|---|---|---| | is small, and needs one set of rights | one agent, more tools | delegation | every piece handed on is a piece of work of its own, with its own model calls | | has parts that need different rights | [[agent-delegation\|delegation]] | one agent with every role | a specialist acts with its own agent's roles, so no agent holds more than its part needs | | has parts that can be done at the same time | delegation | one agent doing them in turn | pieces asked for in one turn run side by side | | has a part that must not spend past a share | delegation with `budget:` | one limit for everything | a piece that runs out is stopped alone; the rest goes on | | has parts that people correct separately | a skill each, or an agent each | one large skill | corrections and instructions are kept for each agent and skill | ### Who approves: a queue or a person? {#queue-or-person} | The decision | Use | Not | Because | |---|---|---|---| | is the asker's own to make | nothing: it goes to the person the work is for | a queue | their yes runs it with their own rights | | is made in a process, where nobody is signed in | nothing: it goes to the agent's sponsor — or `.For(person)` on the step | a queue nobody watches | somebody always answers for an agent | | belongs to a role with several holders | [[agent-autonomy#route\|`ProposalRoute.ToQueue("Finance")`]], a restricted queue | the person who asked | whoever works that queue decides, and the asker is refused even when they work it too | | belongs to exactly one office holder | `ProposalRoute.ToPerson(account)` | a queue of one | it is put to them by name | | must not wait when that person is away | the policy [[agent-roles#deciders\|`DecidesAgentProposals`]] | sharing an account | whoever it admits may decide a proposal put to somebody else | A queue that is not restricted is worked by everybody who works the inbox. Restrict the queue a routed proposal goes to. See [The WorkQueues kit — queues, who holds what, and the service levels promised on any item](https://osysharp.com/reference/workflow/inbox-kit/). ### When does each Privacy kit arrive? {#privacy} You add [Osysharp.Privacy](https://osysharp.com/reference/agent/kit-privacy/) when the app holds personal data and must answer a person who asks what is held, or asks to be erased. The four below are never written in a manifest: each arrives by itself when the app uses both kits it sits between. | The app uses Privacy and | It gets | It covers | You write | |---|---|---|---| | [[agent-kit-agents\|Agents]] | [[agent-kit-privacy-agents\|Privacy.Agents]] | what agents did for a person and about a person | `MarkAgentWorkAbout(task, subject)` for work *about* somebody | | [[agent-kit-llm\|Llm]] | [[agent-kit-privacy-llm\|Privacy.Llm]] | the model calls made for a person; the meter keeps no text | nothing | | [[agent-kit-assignments\|Assignments]] | [[agent-kit-privacy-assignments\|Privacy.Assignments]] | the people on an assignment and the person it is about | `MarkAssignmentAbout(a, subject)` | | [[agent-kit-work-repositories\|WorkRepositories]] | [[agent-kit-privacy-work-repositories\|Privacy.WorkRepositories]] | the items a piece of work keeps about a person, each kind for its own time | `MarkItemAbout(item, subject)` | More: [Privacy for the agent family — agents, the model meter, assignments and work repositories under a person's request](https://osysharp.com/reference/agent/privacy/). ### How do I test without a model? {#testing} | I want to test | Use | Because | |---|---|---| | one model call | [[agent-llm-scripted-model\|`ScriptedModel` and `ScriptedAnswer.Stub`]] | routing, limits and the meter are the real ones; only the provider is scripted | | what an agent does | [[agent-testing\|`AgentScript.Of(Says.Tool(…), Says.HandBack(…))`]], then `Trajectory.Of(task)` | the script says what the model answers turn by turn; the test reads back what the agent then did | | several agents at once | [[agent-testing#cast\|`AgentCast`]] | each agent gets its own script; `Trajectory.Tree` reads the tree back | | a whole process | [[agent-testing#process\|`ProcessTrail`]] | which skills ran, in which states, how each ended, what it cost | | a person's answer | `runas (Person) { ApproveAgentProposal(…) }` or `AnswerRequest(…)` | the yes runs as that person, exactly as on screen | | a wait of days | `TestClock.Advance(TimeSpan.FromDays(3))` | nothing sleeps; the test asserts no model was asked meanwhile | | a provider that is down | throw `ExternalServiceException` from the script | fallback, retries and the failure branch are then real | None of it costs anything or needs a key. Every example in this guide is tested this way. ## What to read next {#read-next} - [The six decisions — what you say about an agent, and what holds if you say nothing](https://osysharp.com/reference/agent/guide-decisions/) — the six decisions these tables belong to - [The map of the kits — which sits on which, and what each one is for](https://osysharp.com/reference/agent/guide-kits/) — the kits named in the tables, on one map - [Glossary — the words the Agents guide uses](https://osysharp.com/reference/agent/guide-glossary/) — every term used here ## Go deeper {#see-also} - [What an agent does alone, what it proposes, what it never does — the gate and proposals (Agents kit)](https://osysharp.com/reference/agent/autonomy/) — the gate, proposals, routing, standing rules - [An agent hands work on to other agents — at once, typed, and never with more than it holds (Agents kit)](https://osysharp.com/reference/agent/delegation/) — handing work on - [Assignments — a piece of work owned until its outcome is reached (Assignments kit)](https://osysharp.com/reference/agent/assignments/) — a piece of work owned until its outcome is reached - [Agents in business processes — an agent's work as a step of a workflow, told on the run (Agents.Processes kit)](https://osysharp.com/reference/agent/processes/) — an agent's work as a step of a process - [Privacy for the agent family — agents, the model meter, assignments and work repositories under a person's request](https://osysharp.com/reference/agent/privacy/) — the four holders, and what an erasure leaves - [Testing an agent without a model — Says, AgentScript and Trajectory (Agents.Testing kit)](https://osysharp.com/reference/agent/testing/) — scripting the model