Add support for Actorized MCP server to `call-actor` tool

[MQ37]

Right now the Actorized MCP servers cannot be used through the call-actor tool. We need to figure out a way how to support them through this tool. Maybe leverage the multi-step nature the tool?

[MichalKalita]

My proposal:

1. When Actor is Actorized MCP. It must not be possible to use it as a standard Actor.
2. Call-actor tool will have optional parametr "tool-name"
3. When call-actor have step=info, tool-name is ignored
4. When call-actor have step=call, tool-name is required
5. This MCP server must create and close sessions for each request. In the other case, there will be long-time living sessions where users will pay for the Actor runtime.

@jirispilka @MQ37

I forgot about
6. In step info, call-actor must return list of tools with descriptions

[MQ37]

My proposal:

1. When Actor is Actorized MCP. It must not be possible to use it as a standard Actor.

2. Call-actor tool will have optional parametr "tool-name"

3. When call-actor have step=info, tool-name is ignored

4. When call-actor have step=call, tool-name is required

5. This MCP server must create and close sessions for each request. In the other case, there will be long-time living sessions where users will pay for the Actor runtime.

@jirispilka @MQ37

I forgot about 6. In step info, call-actor must return list of tools with descriptions

This high level overview looks reasonable to me 👍

[jirispilka]

I’m not really sure what we need to solve this use case.

In the info step, you need to fetch all the tools and their schemas (which basically means starting an Actor). After that, you can call it.

I mean, I can image the use-case but I don't think it is worth solving as of now.

[MichalKalita]

It's blocking when user wants, for example, to use Kiwi MCP server, but it doesn't work.