Standardize on AGENTS.md on .agentignore Format Support

[stevemoser]

This is a proposal to support the AGENTS.md and .agentignore formats in Agent-Client-Protocol (ACP)

1. AGENTS.md is a standardized file for providing instructions and capabilities to AI agents.

2. .agentignore is a standardized file for specifying files and directories that AI agents should ignore (similar to .gitignore). Support for .agentignore has been proposed in the AGENTS.md project: Specification Extension Request: Standardized ignore files Support in Agents.md Specification openai/agents.md#33

Motivation

The agent-client-protocol, being a standard for communication between editors and agents, is well positioned to support the AGENTS.md and .agentignore formats.

Adopting AGENTS.md and .agentignore will create a more consistent and predictable experience for developers and it will allow them to easily switch between coding agents.

Proposed Solution

1. Adopt AGENTS.md: The agent-client-protocol should recognize AGENTS.md as the standard file for agent instructions. This file would provide a centralized place for developers to define the agent's purpose, capabilities, and any other relevant information.

2. Adopt .agentignore: The protocol should also adopt .agentignore as the standard for specifying files and directories to be ignored by the agent.

The agent-client-protocol specification should be modified to specify on how clients should discover, parse, and utilize both AGENTS.md and .agentignore.

[benbrandt]

@stevemoser can you explain more the problem you are trying to solve with this?
We kind of assume the agents, not the client, would be handling these sorts of decisions. However, maybe the agent could let the client know which instructions/rules it is using? So the client could display to the user what is being used?

Would that solve the issue you are having? If not, let me know what it is you are thinking.

[stevemoser]

Yes displaying the rules in use would be very helpful. I see the believe the most salient part is that the client enforces which files are visible to the agent. This is especially important from a security standpoint for .env files.