---
title: "FusionServerToolConfig"
---

Configuration for the openrouter:fusion server tool.


## Fields

| Field                                                                                                                                                                                                                                                                                                                                                           | Type                                                                                                                                                                                                                                                                                                                                                            | Required                                                                                                                                                                                                                                                                                                                                                        | Description                                                                                                                                                                                                                                                                                                                                                     | Example                                                                                                                                                                                                                                                                                                                                                         |
| --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `analysis_models`                                                                                                                                                                                                                                                                                                                                               | List[*str*]                                                                                                                                                                                                                                                                                                                                                     | :heavy_minus_sign:                                                                                                                                                                                                                                                                                                                                              | Slugs of models to run in parallel as the analysis panel. Each model receives the user prompt with openrouter:web_search and openrouter:web_fetch enabled, then a judge model summarizes the collective output into structured analysis JSON. Capped at 8 models to bound cost amplification. Defaults to the Quality preset from /labs/fusion.                 | [<br/>"~anthropic/claude-opus-latest",<br/>"~openai/gpt-latest",<br/>"~google/gemini-pro-latest"<br/>]                                                                                                                                                                                                                                                          |
| `cache_control`                                                                                                                                                                                                                                                                                                                                                 | [Optional[components.AnthropicCacheControlDirective]](../components/anthropiccachecontroldirective.mdx)                                                                                                                                                                                                                                                          | :heavy_minus_sign:                                                                                                                                                                                                                                                                                                                                              | Enable automatic prompt caching. When set at the top level, the system automatically applies cache breakpoints to the last cacheable block in the request. Currently supported for Anthropic Claude models.                                                                                                                                                     | \{<br/>"type": "ephemeral"<br/>}                                                                                                                                                                                                                                                                                                                                 |
| `max_completion_tokens`                                                                                                                                                                                                                                                                                                                                         | *Optional[int]*                                                                                                                                                                                                                                                                                                                                                 | :heavy_minus_sign:                                                                                                                                                                                                                                                                                                                                              | Maximum number of output tokens (including reasoning tokens) each panelist and the judge model may produce per inner call. Controls the total output budget so reasoning-heavy models like GPT-5.5 do not exhaust their token allowance before producing visible text. When omitted, panelists default to 32000 and the judge to 50000.                         | 16384                                                                                                                                                                                                                                                                                                                                                           |
| `max_tool_calls`                                                                                                                                                                                                                                                                                                                                                | *Optional[int]*                                                                                                                                                                                                                                                                                                                                                 | :heavy_minus_sign:                                                                                                                                                                                                                                                                                                                                              | Maximum number of tool-calling steps each panelist (analysis model) and the judge model may take during their agentic web-research loop. Models with web_search/web_fetch enabled iterate until they produce a text response or hit this ceiling. Defaults to 8. Capped at 16.                                                                                  | 12                                                                                                                                                                                                                                                                                                                                                              |
| `model`                                                                                                                                                                                                                                                                                                                                                         | *Optional[str]*                                                                                                                                                                                                                                                                                                                                                 | :heavy_minus_sign:                                                                                                                                                                                                                                                                                                                                              | Slug of the judge model that produces the structured analysis JSON. Defaults to the model used in the outer API request.                                                                                                                                                                                                                                        | ~anthropic/claude-opus-latest                                                                                                                                                                                                                                                                                                                                   |
| `reasoning`                                                                                                                                                                                                                                                                                                                                                     | [Optional[components.FusionServerToolConfigReasoning]](../components/fusionservertoolconfigreasoning.mdx)                                                                                                                                                                                                                                                        | :heavy_minus_sign:                                                                                                                                                                                                                                                                                                                                              | Reasoning configuration forwarded to panelist and judge inner calls. Use this to control reasoning effort and token budget for models that support extended thinking.                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                 |
| `temperature`                                                                                                                                                                                                                                                                                                                                                   | *Optional[float]*                                                                                                                                                                                                                                                                                                                                               | :heavy_minus_sign:                                                                                                                                                                                                                                                                                                                                              | Temperature forwarded to panelist inner calls. The judge always runs at temperature 0 regardless of this value. When omitted, the provider's default applies.                                                                                                                                                                                                   | 0.7                                                                                                                                                                                                                                                                                                                                                             |
| `tools`                                                                                                                                                                                                                                                                                                                                                         | List[[components.FusionServerToolConfigTool](../components/fusionservertoolconfigtool.mdx)]                                                                                                                                                                                                                                                                      | :heavy_minus_sign:                                                                                                                                                                                                                                                                                                                                              | Server tools available to panelist and judge inner calls. Each entry uses the same `{ type, parameters? }` shorthand as the outer Chat Completions request. When omitted, defaults to `[{ type: "openrouter:web_search" }, { type: "openrouter:web_fetch" }]`. Pass an empty array to disable tools entirely (panelists answer from parametric knowledge only). | [<br/>\{<br/>"parameters": \{<br/>"excluded_domains": [<br/>"example.com"<br/>]<br/>},<br/>"type": "openrouter:web_search"<br/>},<br/>\{<br/>"type": "openrouter:web_fetch"<br/>}<br/>]                                                                                                                                                                            |