> ## Documentation Index > Fetch the complete documentation index at: https://developers.telnyx.com/llms.txt > Use this file to discover all available pages before exploring further. # Attach a policy > Applies a policy to every request, or to the requests for the models named. It applies from the next request on. ## OpenAPI ````yaml /openapi/source/external/agent-gateway/agent-gateway.json post /agent_gateways/{instance_id}/policy_attachments openapi: 3.1.0 info: version: 1.0.0 title: Telnyx API x-latency-category: interactive x-endpoint-cost: light description: >- Agent Gateway authenticates, authorizes, and audits the requests agents send to models, tools, and other agents. Each gateway runs as a dedicated instance on the account's [*Network*](https://developers.telnyx.com/docs/network/overview). This API creates, lists, and deletes instances, and manages the keys, teams, spend logs, MCP servers, APIs, tool permissions, and guardrails on them. Each instance serves an OpenAI-compatible API at its `gateway_url`. servers: - url: https://api.telnyx.com/v2 description: Telnyx API v2 security: - bearerAuth: [] tags: - name: Agent Gateways description: Create, list, retrieve, and delete Agent Gateway instances. - name: Agent Gateway Keys description: Keys on an instance. - name: Agent Gateway Teams description: 'Teams on an instance: shared model lists, budgets, and rate limits.' - name: Agent Gateway Spend Logs description: The requests an instance served, with their cost. - name: Agent Gateway MCP Servers description: MCP servers on an instance, served to agents at one MCP endpoint. - name: Agent Gateway APIs description: REST APIs on an instance, served to agents as tools. - name: Agent Gateway Tool Permissions description: The MCP servers and tools a key or team may use. - name: Agent Gateway Guardrails description: Checks an instance runs on model and tool requests. - name: Agent Gateway Policies description: Named sets of guardrails an instance applies to requests. - name: Agent Gateway Policy Attachments description: Where an instance applies each policy. paths: /agent_gateways/{instance_id}/policy_attachments: post: tags: - Agent Gateway Policy Attachments summary: Attach a policy description: >- Applies a policy to every request, or to the requests for the models named. It applies from the next request on. operationId: CreateAgentGatewayPolicyAttachment parameters: - name: instance_id in: path required: true description: The Agent Gateway's `id`. schema: type: string format: uuid example: 32ce035d-3165-4031-b1a7-a7c0c259590a requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/AgentGatewayPolicyAttachmentCreate' examples: models: summary: Some models, with a priority value: policy: strict models: - GLM-5.3* priority: 10 default: summary: The default value: policy: baseline default: true responses: '201': description: The attachment content: application/json: schema: $ref: '#/components/schemas/AgentGatewayPolicyAttachmentResponse' example: data: id: 3394712f-2ad5-428a-8a3d-7a08d4b2906d policy: strict models: - GLM-5.3* priority: 10 default: false created_at: '2026-11-02T12:58:55.388000Z' updated_at: '2026-11-02T12:58:55.388000Z' '400': description: A policy the instance does not have content: application/json: schema: $ref: '#/components/schemas/TelnyxErrors' example: errors: - code: '10013' title: Missing association detail: One of the associated fields does not exist. meta: url: https://developers.telnyx.com/docs/overview/errors/10013 source: pointer: /policy '401': description: Unauthorized content: application/json: schema: $ref: '#/components/schemas/TelnyxErrors' example: errors: - code: '10009' title: Authentication failed detail: >- The required authentication headers were either invalid or not included in the request. meta: url: https://developers.telnyx.com/docs/overview/errors/10009 '404': description: Not found content: application/json: schema: $ref: '#/components/schemas/TelnyxErrors' example: errors: - code: '10005' title: Resource not found detail: The requested resource or URL could not be found. meta: url: https://developers.telnyx.com/docs/overview/errors/10005 components: schemas: AgentGatewayPolicyAttachmentCreate: type: object required: - policy properties: policy: type: string description: The policy to apply, by name. models: type: array items: type: string default: [] description: >- The models whose requests the policy applies to, by name. A name can use `*` as a wildcard. Empty applies the policy to every request. priority: anyOf: - type: integer - type: 'null' description: An attachment with a priority applies before the others. default: type: boolean default: false description: >- `true` applies the policy only to the requests no other attachment matches. AgentGatewayPolicyAttachmentResponse: type: object required: - data properties: data: $ref: '#/components/schemas/AgentGatewayPolicyAttachment' TelnyxErrors: type: object properties: errors: type: array items: $ref: '#/components/schemas/TelnyxError' AgentGatewayPolicyAttachment: type: object description: Where an instance applies a policy. required: - id - policy - models - priority - default - created_at - updated_at properties: id: type: string format: uuid description: The attachment's ID. policy: type: string description: The policy to apply, by name. models: type: array items: type: string default: [] description: >- The models whose requests the policy applies to, by name. A name can use `*` as a wildcard. Empty applies the policy to every request. priority: anyOf: - type: integer - type: 'null' description: An attachment with a priority applies before the others. default: type: boolean default: false description: >- `true` applies the policy only to the requests no other attachment matches. created_at: anyOf: - type: string format: date-time - type: 'null' description: When the attachment was created. updated_at: anyOf: - type: string format: date-time - type: 'null' description: When the attachment last changed. TelnyxError: type: object properties: code: type: string title: type: string detail: type: string source: type: object properties: pointer: type: string parameter: type: string meta: type: object properties: url: type: string securitySchemes: bearerAuth: type: http scheme: bearer description: Telnyx API key ````