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D3 The Responses API and Built-in Tools: Function Calling, Web Search / File Search / Computer Use, Structured Output

• When do you use platform built-in tools (web search, file search, computer use) versus your own function tools, and why does computer use deserve special treatment?平台内置的工具（web search、file search、computer use）和自己写的函数工具，各适合什么场景？为什么 computer use 要单独对待？

  Common in ChinaCommon overseasIntermediate#tools#responses-api#security

  How to reason about it · think before answering

  1. Two cruxes: who executes the tool, and how large its side effects are; comparing features alone signals no production experience.
  2. Executor test: built-in tools run server-side, you declare but never fill results and cannot steer the search; function tools run in your code, more work but full control.
  3. Map to scenarios: external, generic data (the web, your uploaded documents) fits built-ins; data inside your systems (databases, internal services, business logic) needs functions; production mixes both.
  4. Order by side effects: web search reads the public web, file search reads your files, function calls have whatever side effects your code allows, computer use lets the model act directly; more capability demands heavier isolation.
  5. Computer use is special because it can click anything, type anything and be steered by on-screen content, so the starting point is an isolated environment, a restricted account and an allow-list, not code.
  6. Expect the follow-up: built-in file search versus your own RAG? The built-in is a managed pipeline that skips chunking, embedding and retrieval work at the cost of control and observability; build your own when you need custom chunking or reranking.

  分析过程 · 先想清楚再作答

  1. 题眼有两个：一是「谁来执行」，二是「副作用有多大」。只答功能对比不谈执行方与风险，就是没做过工程。
  2. 先给执行方的判据：内置工具由平台在服务端执行，你只声明、不回填、也控制不了它怎么搜；函数工具由你执行，样样自己写，但每一步都在你手里。
  3. 落到场景：数据在外面且通用（公网、你上传的文档）用内置工具；数据在你系统里（数据库、内部服务、业务逻辑）写函数；生产系统几乎总是混用。
  4. 再按副作用排一条光谱：web search 只读公网，file search 只读你给的文件，函数调用的副作用由你的代码决定，computer use 由模型直接产生副作用——越往右能力越强，需要的隔离越重。
  5. computer use 单独对待的原因：它能点任何按钮、输任何文字，还可能被页面内容诱导，所以正确起点是隔离环境、受限账号和站点与动作白名单，不是代码。
  6. 可预期的追问：内置的 file search 和自己搭 RAG 怎么选？前者是托管版，省掉切分、向量化、检索三步，代价是可控性与可观测性弱，需要自定义切分或重排时才自己搭。

  Key points

  • Built-ins run on the platform with no result filling and no steering; functions run in your code with full control
  • External generic data suits built-ins, in-system data and business logic need functions, production mixes both
  • Rank by side effects: web search, file search, function calls, computer use; more power needs more isolation
  • Computer use starts with an isolated environment and an allow-list, not with code

  答题要点

  • 内置工具由平台执行、不用回填、不可干预；函数工具由你执行、全部可控
  • 外部通用数据用内置工具，系统内数据与业务逻辑写函数，生产混用
  • 按副作用排序：web search、file search、函数调用、computer use，能力越强隔离越重
  • computer use 的起点是隔离环境与白名单，不是代码