Use application tools

Know which tools your server executes

Application tools describe functions that your code executes. SERV Tools are control markers that SERV consumes before the model runs. SERV recognizes a fixed set of marker names; use the documented names for SERV features. You can put both kinds in one tools array. SERV removes its marker tools and forwards your application tools unchanged. The model can call get_order, but it never calls serv_prompt_guard or serv_shadow_agent.

SERV Tool	Endpoint support	Constraint
`serv_prompt_guard`	Chat Completions, Responses, Messages	Runs before the requested model
`serv_shadow_agent`	Chat Completions, Responses, Messages	Non-streaming requests only
`serv_disable_content_filter`	Chat Completions and Responses	Disables the default output leak detector

const response = await client.chat.completions.create({
  model: "gpt-5.4-mini",
  messages: [
    { role: "system", content: "Use get_order for order status. Never guess." },
    { role: "user", content: "What is the status of order 1842?" },
  ],
  tools: [{
    type: "function",
    function: {
      name: "get_order",
      description: "Look up an order by its ID.",
      parameters: {
        type: "object",
        properties: { order_id: { type: "string" } },
        required: ["order_id"],
        additionalProperties: false,
      },
    },
  }],
});

When the model calls an application tool, your server executes it and sends the result in a follow-up request. SERV forwards unrecognized tools normally, even when their names begin with serv_. State when the model should call each tool, define a strict input schema, and validate every argument before performing a side effect. Put the tool-use policy in the system prompt. For example: “Use get_order for every order-status question. Never guess an order status.”

Combine application tools with SERV Tools

The same request can enable SERV protection, quality validation, and an application function:

tools: [
  { type: "function", function: { name: "serv_prompt_guard" } },
  {
    type: "function",
    function: {
      name: "serv_shadow_agent",
      parameters: {
        type: "object",
        properties: { hint: { type: "string", default: "Cite the order status returned by the tool." } },
      },
    },
  },
  {
    type: "function",
    function: {
      name: "get_order",
      description: "Look up an order by its ID.",
      parameters: {
        type: "object",
        properties: { order_id: { type: "string" } },
        required: ["order_id"],
        additionalProperties: false,
      },
    },
  },
]

SERV consumes the first two markers. Only get_order reaches the model. Your server remains responsible for executing get_order, checking the arguments, and handling the follow-up conversation. Setting x-openserv-disable-braid: true bypasses the SERV Tools as well as reasoning-prompt generation.

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Know which tools your server executes

Combine application tools with SERV Tools

​Know which tools your server executes

​Combine application tools with SERV Tools

Know which tools your server executes

Combine application tools with SERV Tools