Implementation Notes

Why policy hooks were added now

Your MTP direction includes operational safety and practical adoption. A protocol that only routes tool calls but has no execution-policy layer is hard to ship in production.

Current behavior:

• read_only tools: default allow
• write tools: default allow
• destructive tools: default ask (blocked until approval flow is added)

This is configurable via RiskPolicy.

Why plan validation is strict

If a provider emits invalid plan graphs, runtime errors become hard to debug. We validate before execution to fail fast and clearly.

Why tool control-flow exceptions were added

Complex tool ecosystems need explicit signals to control the loop:

• RetryAgentRun: feed correction guidance back to the model and replan.
• StopAgentRun: intentionally stop/pause for continuation or user intervention.

These signals now travel from tool handler -> runtime -> agent loop without being flattened into generic tool errors.

Why async provider hooks were added

Agent async APIs now support provider-native async paths (anext_action, afinalize). If a provider only has sync methods, MTP uses thread fallback automatically. This keeps compatibility while preventing async app blocking when async hooks are implemented.

Why run continuation exists

continue_run() and acontinue_run() enable pause/resume flows with preserved message/tool context. This is especially useful when a run intentionally pauses via StopAgentRun.

Compatibility with your MTP vision

Implemented now:

• lazy loading support in runtime
• batch execution semantics
• plan format with dependencies
• safety policy hook
• multi-provider adapter set (Groq/OpenAI/OpenRouter/Gemini/Anthropic/SambaNova)
• multi-provider adapter set (Groq/OpenAI/OpenRouter/Gemini/Anthropic/SambaNova/Cerebras/DeepSeek/Mistral/Cohere/TogetherAI/FireworksAI)
• run continuation and pause semantics
• structured input schema validation
• output model/parser model refinement pipeline
• dynamic tool updates (add_tool, set_tools)
• session persistence (JsonSessionStore, PostgresSessionStore, MySQLSessionStore)

Still needed to reach full ecosystem/library maturity:

• CLI scaffolding
• deeper provider feature parity and capability matrix
• docs site and benchmark suite

Related:

• Storage and Sessions