Initial Checks

• I confirm that I'm using the latest version of Pydantic AI
• I confirm that I searched for my issue in https://github.com/pydantic/pydantic-ai/issues before opening this issue

Description

According to A2A spec - for main communication "message/send" and "message/stream" RPC methods are used (https://google.github.io/A2A/specification/#71-messagesend).

in FastA2A seems that "tasks/send" is the main RPC method but I believe it does the right job just has confusing method name value. (https://github.com/pydantic/pydantic-ai/blob/v0.2.6/fasta2a/fasta2a/applications.py)

I couldn't find any "tasks/send" method explanation in A2A spec (only "tasks/get" seems to be there).

there are more method examples in Google's demo (https://github.com/google/A2A/blob/6743038e9f789f571d7f3d9af79fbb053bb61a73/demo/ui/service/server/server.py#L64) but for most of them I couldn't find any info in spec.

However I believe "message/send" and "message/stream" RPC methods suppose to be supported.

Example Code

Python, Pydantic AI & LLM client version

python : 3.13.2
pydantic(ai) : 0.2.6
LLM - local