# Agent and Model Development

An agent is a bounded package-defined capability. A model is a replaceable inference capability. A workflow is the durable process that invokes agents, deterministic steps, review gates and tools. They have distinct identities and lifecycles.

## Implement the invocation contract

Use the [platform execution contract](/documentation/platform/agentic-platform) for actor, tenant, purpose, schema versions, authorized context references, budgets and trace identity. Return schema-valid outputs, evidence references, uncertainty or abstention, model/tool provenance and a bounded completion state. A package does not invent new authority from retrieved content.

## Model capabilities

Bind a task to a declared ModelPackage capability instead of embedding one provider or model name in business logic. Qualification identifies exact model, runtime, quantization, adapter, hardware and task/language profile. A replacement must satisfy the consuming package's schema, quality, latency and policy requirements.

## Tools and effects

Declare tool schemas, requested scopes, timeout and retry behavior. Use the gateway for policy enforcement and audit. External writes are reviewable intents with approval, idempotency and compensation; agents do not hold unrestricted credentials or write around the gateway.

## Framework adapters

Native SDK implementations and qualified framework adapters map to the same canonical invocation, event, tool, output and audit contracts. A framework session does not replace the durable workflow or environment lock. See [runtime technology profiles](/documentation/platform/agentic-llm-technology) for the compatibility baseline.

## Evidence and evaluation

Reference source versions and the precise supporting fragments for material assertions. Test unsupported claims, conflicting evidence, prompt injection, unauthorized sources, ambiguous identities and low-coverage cases. Domain evaluation fixtures belong to the package; the platform supplies execution, recording and admission controls.

## Concrete implementations

The [agent ownership index](/documentation/packages/agent-index) links all supplied agents to their canonical package reference. Those manuals contain agent-specific triggers, inputs, outputs, tools, limits and metrics. Reuse a declared capability rather than creating a second conflicting copy of its agent.