[Feature Request] A2A protocol host should support passing Bearer token at runtime for MCP tools

[itsdruvaraj]

Summary

A2A (Agent-to-Agent) protocol hosts should support passing Bearer tokens to MCP tools at runtime when using existing Foundry agents.

Problem

When hosting an existing Azure AI Foundry agent via A2A protocol, there's no way to pass dynamic Bearer tokens to MCP tools during RunAsync() calls. The token must be configured at agent creation time, which doesn't work for A2A hosts that need runtime authentication.

Requested Enhancement

Support passing Bearer token headers through AgentRunOptions or McpServerToolApprovalResponseContent when invoking an existing agent.

Environment

• .NET 10 SDK
• Microsoft.Agents.AI 1.0.0-preview
• Azure.AI.Agents.Persistent (latest preview)

[markwallace-microsoft]

@SergeyMenshykh Is there a way to achieve this?

[SergeyMenshykh]

@itsdruvaraj, this PR: #3137 enables scenarios where additional data can be passed from the client over the wire to the server that hosts an agent as A2A.