Server Tools

Server tools are tools that Phaseo runs for you during a model request. The model decides when to call them, Phaseo executes the tool server-side, and the tool result is fed back into the model loop. Use server tools when the model needs current time, web context, fetched page text, or a second model’s advice without adding your own tool executor.

Server tools are in beta. Request shapes and result payloads may evolve as provider support changes.

Available tools

Tool	Type	Use it for
Datetime	`phaseo:datetime`	Current date and time in up to 5 timezones
Web Search	`phaseo:web_search`	Model-directed web searches during a request
Web Fetch	`phaseo:web_fetch`	Fetching and extracting text from specific URLs
Advisor	`phaseo:advisor`	Consulting another model mid-generation
Subagent	`phaseo:subagent`	Delegating focused work to a worker model
Fusion	`phaseo:fusion`	Parallel analysis followed by model synthesis
Search Models	`phaseo:search_models`	Finding suitable models from the live catalogue
Image Generation	`phaseo:image_generation`	Creating images from the model tool loop
Apply Patch	`phaseo:apply_patch`	Producing validated file patches on the Responses API

How server tools work

Add one or more server tools to the tools array.
The model decides whether it needs a tool and emits a tool call.
Phaseo intercepts the server-tool call, executes it, and sends the result back to the model.
The model continues and writes the final response.

Server tools can be used alongside your own function tools. Phaseo executes only the server tools; your application still handles regular function tool calls.

Quick start

curl https://api.phaseo.app/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5-nano",
    "messages": [
      { "role": "user", "content": "What are the latest AI policy updates this week?" }
    ],
    "tools": [
      { "type": "phaseo:web_search" },
      { "type": "phaseo:datetime", "parameters": { "timezones": ["Europe/London", "UTC"] } }
    ]
  }'

Combining with function tools

{
  "model": "openai/gpt-5-nano",
  "messages": [
    { "role": "user", "content": "Find recent funding news and save the best item." }
  ],
  "tools": [
    { "type": "phaseo:web_search", "parameters": { "max_results": 3 } },
    {
      "type": "function",
      "function": {
        "name": "save_research_item",
        "description": "Save a selected research item",
        "parameters": {
          "type": "object",
          "properties": {
            "title": { "type": "string" },
            "url": { "type": "string" }
          },
          "required": ["title", "url"]
        }
      }
    }
  ]
}

If the model calls phaseo:web_search, Phaseo executes that call automatically. If it calls save_research_item, your application receives the function call and must return the function result in a follow-up request.

Supported endpoints

Server tools are supported on:

/v1/chat/completions
/v1/responses
/v1/messages

Streaming requests are supported. For gateway-managed server tools, Phaseo may materialize the upstream tool-call turn, execute the server tool, continue the loop, and emit a synthetic stream for the final response.

Usage tracking

Server-tool usage is reported in usage.server_tool_use:

{
  "usage": {
    "input_tokens": 105,
    "output_tokens": 250,
    "server_tool_use": {
      "datetime_requests": 1,
      "web_search_requests": 2,
      "web_search_results": 8,
      "web_fetch_requests": 1,
      "advisor_requests": 1,
      "subagent_requests": 1,
      "fusion_requests": 1,
      "search_models_requests": 1,
      "image_generation_requests": 1
    }
  }
}

Pricing can also use server-tool meters such as server_tool_web_search_requests, server_tool_web_search_extra_results, server_tool_web_fetch_requests, server_tool_advisor_requests, server_tool_image_generation_requests, native_web_search_requests, and native_web_fetch_requests when configured on model price cards.

Tool pages

Datetime

Give the model the current date and time.

Web Search

Let the model search the web when it needs current information.

Web Fetch

Let the model fetch and read specific URLs.

Advisor

Let one model consult another model for guidance mid-generation.

Subagent

Let the model delegate focused tasks to a worker model.

Fusion

Run parallel model analysis and synthesize the findings.

Search Models

Let the model search the live Phaseo catalogue for a suitable model.

Image Generation

Let the model create images while answering.

Apply Patch

Generate a validated create, update, or delete patch.

Overview

Models & Routing

Features

Integrations

Workspace & Access

Reliability & Operations

Platform & Research

Migration Guides

Community

Available tools

How server tools work

Quick start

Combining with function tools

Supported endpoints

Usage tracking

Tool pages

Datetime

Web Search

Web Fetch

Advisor

Subagent

Fusion

Search Models

Image Generation

Apply Patch

​Available tools

​How server tools work

​Quick start

​Combining with function tools

​Supported endpoints

​Usage tracking

​Tool pages

Datetime

Web Search

Web Fetch

Advisor

Subagent

Fusion

Search Models

Image Generation

Apply Patch

Available tools

How server tools work

Quick start

Combining with function tools

Supported endpoints

Usage tracking

Tool pages