Update MCP server tool documentation to cover all available options (#1685)

## Summary
- reorganized the MCP guide with a transport comparison table
- documented hosted MCP tools, approval flows, connectors, and streaming
usage
- refreshed Streamable HTTP, SSE, stdio, and tool-filter sections with
concrete examples and references

## Testing
- make lint
- make tests *(fails: missing optional dependencies `litellm` and
`numpy` during collection)*

------
https://chatgpt.com/codex/tasks/task_i_68be9d56a7748320ae5fec952ec836a9

Author: seratch