> ## Documentation Index
> Fetch the complete documentation index at: https://phaseo.app/docs/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> Phaseo Gateway base URL: https://api.phaseo.app/v1. Send `Authorization: Bearer $PHASEO_API_KEY` with every request.
> Model IDs look like `provider/model`, for example `openai/gpt-6-astra`. Do not guess IDs: list them with `GET /v1/models` or check https://phaseo.app/models. `phaseo/free` routes to an available free model and needs no wallet balance.
> For new text integrations prefer `POST /v1/responses`. `POST /v1/chat/completions` (OpenAI format) and `POST /v1/messages` (Anthropic format) suit existing code.
> The full API contract is https://phaseo.app/docs/openapi/v1/openapi.yaml. Official SDKs: `@phaseo/sdk` (TypeScript) and `phaseo` (Python), plus Go, C#, PHP, Ruby and Rust.
> Search these docs over MCP at https://phaseo.app/docs/mcp, and install Phaseo skills with `npx skills add https://phaseo.app/docs`. If a page is wrong or out of date, report it with the MCP `submit_feedback` tool.
> Manage Phaseo accounts with the `phaseo` CLI (`npm install -g @phaseo/cli`, then `phaseo login` or `phaseo login --device-code`), the `/v1` Management API or the MCP server at `https://mcp.phaseo.app/mcp?access=manage`. Do not send users to the dashboard for account tasks. A person is still needed for sign-up, approving a sign-in, paying the first top-up on the checkout link that `phaseo credits add` returns when no card is saved, confirming each saved-card top-up from the emailed link, and account security (password, MFA, passkeys). Create API keys with `phaseo keys create --name <name> --json`; never guess one. Credit top-ups need `phaseo login --scopes billing:write` first. Task map: https://phaseo.app/docs/v1/developers/manage-from-an-agent.md.

# Rerank Documents

> Order candidate documents by relevance to a query with POST /v1/rerank.

Call `client.rerank.create()` to order candidate documents by relevance to a query with `POST /v1/rerank`. The method has the same name in TypeScript and Python; Rust posts the same JSON with `client.post()`.

```typescript TypeScript theme={null}
import Phaseo from "@phaseo/sdk";

const client = new Phaseo({ apiKey: process.env.PHASEO_API_KEY! });

const result = await client.rerank.create({
  model: "voyage/rerank-2",
  query: "How do I check whether a model is routable?",
  documents: [
    "Call GET /v1/models and use the default availability filter.",
    "Create an image with POST /v1/images/generations.",
  ],
});

console.log(result.results);
```

```python Python theme={null}
from phaseo import Phaseo

client = Phaseo()  # reads PHASEO_API_KEY

result = client.rerank.create({
    "model": "voyage/rerank-2",
    "query": "How do I check whether a model is routable?",
    "documents": [
        "Call GET /v1/models and use the default availability filter.",
        "Create an image with POST /v1/images/generations.",
    ],
})

print(result["results"])
```

```rust Rust theme={null}
// No rerank method yet: post() sends JSON to any Phaseo path.
use phaseo::Phaseo;
use serde_json::json;

let client = Phaseo::from_env()?; // reads PHASEO_API_KEY

let result = client.post("/rerank", &json!({
    "model": "voyage/rerank-2",
    "query": "How do I check whether a model is routable?",
    "documents": [
        "Call GET /v1/models and use the default availability filter.",
        "Create an image with POST /v1/images/generations."
    ]
}))?;

println!("{}", result.body["results"]);
```

**Python:** `client.rerank.create()` posts the dict you pass as the JSON body and returns the JSON response; there's no typed `generate_rerank` helper. On `AsyncPhaseo`, await it.

The Go, C#, PHP, Ruby and Java SDKs have no rerank method. Send `POST /v1/rerank` with your HTTP client, as in the [Rerank API reference](https://phaseo.app/docs/v1/api-reference/endpoint/rerank.md).

Confirm the model ID with `GET /v1/models` before using it in production.

## Parameters

Field names are the JSON body fields in every SDK.

| Field | Notes |
| - | - |
| `model`, `query`, `documents` | Required. `documents` holds at least one string or object. |
| `top_n` | Return only the best `n` results. `top_k` is accepted as an alias. |
| `return_documents` | Include each document in its result. |
| `rank_fields` | For object documents, the fields to rank on. |
| `max_chunks_per_doc`, `max_tokens_per_doc` | Limits for long documents, on providers that support them. |

## Response

`RerankResponse` has `results`, each with the document's `index` in your list, its `relevance_score`, and the `document` when `return_documents` is set, plus `usage`.


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