fix: allow static tool filtering without agent and run_context in MCPServer

[sevakva]

This PR fixes an issue in MCPServer where run_context and agent parameters were required for all tool filtering scenarios, even when using static tool filtering that doesn't need them.

The fix moves the validation check for run_context and agent from the caller level into the dynamic filter branch of _apply_tool_filter.

[seratch]

The _apply_tool_filter method always receives those parameters, so I don't see the necessity of this change. Can you elaborate more on the context?

[sevakva]

The _apply_tool_filter method always receives those parameters, so I don't see the necessity of this change. Can you elaborate more on the context?

Hey @seratch
We have a need to create MCPServer before agent run and have it globally. Then we call .list_tools() method to construct a global list of tools on startup, so frontend can fetch it.
Calling this method outside of the agent run with static filter causing an error

[seratch]

Ah, I see. This makes sense.