Override aiXplain tool parameters in agent create/run payloads (SDK)

[aix-ahmet]

Summary

Add support for setting/overriding per-tool parameters on aiXplain tools attached to an agent, in both the create and run payloads. This is the SDK half of PROD-2481 (engine half tracked separately in aixplain/aixplain-agents).

Today only role models (llm/supervisor/planner/responder) accept {id, parameters} and support run-time override via modelParameters. Tools snapshot their params only at save time (as_tool() / get_parameters()) and have no run-time override path.

User-facing shape

tools is a list of dicts, each carrying its own params — same shape at create and run:

# creation
agent = Agent(name="...", tools=[
    {"id": "<tool_id>", "parameters": {"top_k": 5, "filters": {...}}},
    {"id": "<other_id>", "parameters": {"language": "es"}},
])
agent.save()

# run (overrides persisted params by tool id)
agent.run(query="...", tools=[{"id": "<tool_id>", "parameters": {"top_k": 8}}])

Mirrors the existing role-model shape (agent.llm = {"id": ..., "parameters": {...}}).

Work (aixplain/v2/agent.py)

• Accept tools entries as {id, parameters: {...}}; normalize parameters into the API name/value shape in build_save_payload — reuse the existing _params_dict_to_namevalue_list / _normalize_tool_dict_for_api helpers used for role models.
• Forward per-tool params at run time in build_run_payload, mirroring how modelParameters already rides the run payload.
• Keep backward compatibility: plain string tool ids and existing as_tool() dicts must continue to work unchanged.

Decisions (from PROD-2481)

• Params are defaults the LLM can override (engine merges {**parameters, **llm_args}). The SDK side just transports them.
• Run-time tools entries override persisted per-tool params by tool id.

Acceptance criteria

• Create payload carries per-tool parameters in the API name/value shape.
• Run payload carries per-tool params so run(tools=[...]) forwards overrides.
• Backward compatible with existing string-id / as_tool() usage.
• Unit tests for build_save_payload and build_run_payload covering the new shape.

Refs

• Jira: PROD-2481
• Engine issue: aixplain/aixplain-agents (parse + inject)