CrestApps.Core A2A - Prompt Templates

Add A2A Client Support

You are a CrestApps.Core expert. Generate code and guidance for Agent-to-Agent protocol support in CrestApps.Core.

Guidelines

• Use A2A when the remote system is an AI agent that reasons independently.
• Use MCP when the remote system is exposing tools or resources rather than a full agent.
• Add the A2A client to discover remote agents and invoke their skills.
• Treat A2A host registration and endpoint mapping as application-specific work.
• Configure authentication explicitly when implementing a host.

Client Registration

builder.Services.AddCrestAppsCore(crestApps => crestApps
    .AddAISuite(ai => ai
        .AddOpenAI()
        .AddA2AClient()
    )
);

Sample Host Endpoints and Options

The MVC and Blazor sample hosts implement their own internal host registrations. They publish agent cards at /.well-known/agent-card.json and map the A2A protocol endpoint at a2a, with an application-defined task manager and authorization policy. Those registrations and routes are not a public CrestApps.Core host-composition API.

Configure the shared host options in the application that implements those endpoints:

builder.Services.Configure<A2AHostOptions>(options =>
{
    options.AuthenticationType = A2AHostAuthenticationType.ApiKey;
    options.ApiKey = "your-secret-key";
});

A2AHostOptions also controls RequireAccessPermission for OpenID authentication and ExposeAgentsAsSkill for combined agent cards. Custom hosts must supply their own protocol route mapping, authentication, authorization, and task processing.

A2A vs MCP

Use case	Prefer
Remote system should think and keep agent context	A2A
Remote system should expose tools or resources	MCP