> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.agentrouter.to/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.agentrouter.to/_mcp/server.

# Get the field-level contract for one capability

GET https://api.agentrouter.to/api/agentic-api/domains/{domainKey}/capabilities/{capabilityId}/contract

Reference: https://docs.agentrouter.to/api-reference/agent-router-api/contracts/get-capability-contract

## OpenAPI Specification

```yaml
openapi: 3.1.0
info:
  title: AgentRouter API
  version: 1.0.0
paths:
  /domains/{domainKey}/capabilities/{capabilityId}/contract:
    get:
      operationId: get-capability-contract
      summary: Get the field-level contract for one capability
      tags:
        - contracts
      parameters:
        - name: domainKey
          in: path
          description: >-
            Domain identifier such as email, search, text, web, enrichment, or
            social.
          required: true
          schema:
            type: string
        - name: capabilityId
          in: path
          description: >-
            Capability identifier inside the selected domain, such as send,
            answer, analyze, people-search, or extract.
          required: true
          schema:
            type: string
      responses:
        '200':
          description: Capability contract for recommend and execute
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CapabilityContract'
        '404':
          description: Requested resource was not found
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
servers:
  - url: https://api.agentrouter.to/api/agentic-api
    description: Hosted AgentRouter API
components:
  schemas:
    CapabilityContractContractStatus:
      type: string
      enum:
        - available
        - partial
        - unavailable
      title: CapabilityContractContractStatus
    CapabilityOperationContractStatus:
      type: string
      enum:
        - available
        - partial
        - unavailable
      title: CapabilityOperationContractStatus
    CapabilityFieldContractType:
      type: string
      enum:
        - string
        - number
        - integer
        - boolean
        - array
        - object
        - unknown
      title: CapabilityFieldContractType
    CapabilityFieldContract:
      type: object
      properties:
        name:
          type: string
        type:
          $ref: '#/components/schemas/CapabilityFieldContractType'
        required:
          type: boolean
        conditionallyRequired:
          type: boolean
        enumValues:
          type: array
          items:
            type: string
        maxLength:
          type: integer
        min:
          type: number
          format: double
        max:
          type: number
          format: double
        itemsType:
          type: string
        fields:
          type: array
          items:
            $ref: '#/components/schemas/CapabilityFieldContract'
        notes:
          type: array
          items:
            type: string
      required:
        - name
        - type
        - required
      title: CapabilityFieldContract
    CapabilityInput:
      type: object
      additionalProperties:
        description: Any type
      description: >-
        Capability-specific request body. Use the contract endpoint for exact
        fields.
      title: CapabilityInput
    CapabilityOperationContract:
      type: object
      properties:
        status:
          $ref: '#/components/schemas/CapabilityOperationContractStatus'
        dtoName:
          type: string
        requiredFields:
          type: array
          items:
            type: string
        optionalFields:
          type: array
          items:
            type: string
        conditionallyRequiredFields:
          type: array
          items:
            type: string
        fields:
          type: array
          items:
            $ref: '#/components/schemas/CapabilityFieldContract'
        requestExample:
          $ref: '#/components/schemas/CapabilityInput'
        responseExample:
          type: object
          additionalProperties:
            description: Any type
        notes:
          type: array
          items:
            type: string
      required:
        - status
        - requiredFields
        - optionalFields
        - conditionallyRequiredFields
        - fields
        - notes
      title: CapabilityOperationContract
    CapabilityContract:
      type: object
      properties:
        domainKey:
          type: string
        capabilityKey:
          type: string
        capabilityId:
          type: string
        docsUrl:
          type: string
          format: uri
        contractStatus:
          $ref: '#/components/schemas/CapabilityContractContractStatus'
        recommend:
          $ref: '#/components/schemas/CapabilityOperationContract'
        execute:
          $ref: '#/components/schemas/CapabilityOperationContract'
        notes:
          type: array
          items:
            type: string
      required:
        - domainKey
        - capabilityKey
        - capabilityId
        - contractStatus
        - notes
      title: CapabilityContract
    ErrorResponse:
      type: object
      properties:
        success:
          type: boolean
        error:
          type: string
        code:
          type: string
        hint:
          type: string
      title: ErrorResponse

```

## Examples



**Response**

```json
{
  "domainKey": "email",
  "capabilityKey": "email.send",
  "capabilityId": "send",
  "contractStatus": "available",
  "notes": [
    "Capability contracts are the canonical place to inspect exact request fields."
  ],
  "docsUrl": "https://docs.agentrouter.to/core-concepts/capability",
  "recommend": {
    "status": "available",
    "requiredFields": [],
    "optionalFields": [
      "agentName",
      "optimizationPreferences",
      "tracking"
    ],
    "conditionallyRequiredFields": [],
    "fields": [
      {
        "name": "agentName",
        "type": "string",
        "required": false
      },
      {
        "name": "optimizationPreferences",
        "type": "array",
        "required": false,
        "itemsType": "string"
      },
      {
        "name": "tracking",
        "type": "boolean",
        "required": false
      }
    ],
    "notes": [
      "Use recommend before execute when the caller has not pinned one provider yet."
    ],
    "dtoName": "RecommendEmailProviderDto",
    "requestExample": {
      "agentName": "alpha_agent",
      "optimizationPreferences": [
        "cost",
        "quality"
      ],
      "tracking": true
    }
  },
  "execute": {
    "status": "available",
    "requiredFields": [
      "to",
      "subject"
    ],
    "optionalFields": [
      "html",
      "text",
      "provider",
      "allowFallback"
    ],
    "conditionallyRequiredFields": [],
    "fields": [
      {
        "name": "to",
        "type": "string",
        "required": true
      },
      {
        "name": "subject",
        "type": "string",
        "required": true
      },
      {
        "name": "html",
        "type": "string",
        "required": false
      },
      {
        "name": "text",
        "type": "string",
        "required": false
      },
      {
        "name": "provider",
        "type": "string",
        "required": false
      },
      {
        "name": "allowFallback",
        "type": "boolean",
        "required": false
      }
    ],
    "notes": [
      "Provide exactly the inner execute body. Do not wrap it again in domain or capability fields."
    ],
    "dtoName": "SendEmailDto",
    "requestExample": {
      "to": "maya@example.com",
      "subject": "Hello from AgentRouter",
      "html": "<p>Hello</p>",
      "provider": "resend",
      "allowFallback": true
    }
  }
}
```

**SDK Code**

```python emailSend
import requests

url = "https://api.agentrouter.to/api/agentic-api/domains/email/capabilities/send/contract"

response = requests.get(url)

print(response.json())
```

```javascript emailSend
const url = 'https://api.agentrouter.to/api/agentic-api/domains/email/capabilities/send/contract';
const options = {method: 'GET'};

try {
  const response = await fetch(url, options);
  const data = await response.json();
  console.log(data);
} catch (error) {
  console.error(error);
}
```

```go emailSend
package main

import (
	"fmt"
	"net/http"
	"io"
)

func main() {

	url := "https://api.agentrouter.to/api/agentic-api/domains/email/capabilities/send/contract"

	req, _ := http.NewRequest("GET", url, nil)

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}
```

```ruby emailSend
require 'uri'
require 'net/http'

url = URI("https://api.agentrouter.to/api/agentic-api/domains/email/capabilities/send/contract")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Get.new(url)

response = http.request(request)
puts response.read_body
```

```java emailSend
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;

HttpResponse<String> response = Unirest.get("https://api.agentrouter.to/api/agentic-api/domains/email/capabilities/send/contract")
  .asString();
```

```php emailSend
<?php
require_once('vendor/autoload.php');

$client = new \GuzzleHttp\Client();

$response = $client->request('GET', 'https://api.agentrouter.to/api/agentic-api/domains/email/capabilities/send/contract');

echo $response->getBody();
```

```csharp emailSend
using RestSharp;

var client = new RestClient("https://api.agentrouter.to/api/agentic-api/domains/email/capabilities/send/contract");
var request = new RestRequest(Method.GET);
IRestResponse response = client.Execute(request);
```

```swift emailSend
import Foundation

let request = NSMutableURLRequest(url: NSURL(string: "https://api.agentrouter.to/api/agentic-api/domains/email/capabilities/send/contract")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "GET"

let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    print(error as Any)
  } else {
    let httpResponse = response as? HTTPURLResponse
    print(httpResponse)
  }
})

dataTask.resume()
```