Context

Foundation for agent capabilities beyond text generation. The tool system allows agents to interact with external systems, files, and services. This issue covers the core architecture: defining tools, registering them, invoking them safely, and returning structured results.

Acceptance Criteria

• Tool base class or Protocol with: name, description, parameters schema, execute method
• Tool Registry with register, lookup, and list operations
• Tool Invoker: matches LLM tool calls to registered tools, validates parameters, invokes execution
• Structured Tool Result format: success/error flag, output data, metadata
• Parameter schemas in LLM-compatible format (JSON Schema or OpenAI function calling format)
• Example tool implemented (echo or calculator) demonstrating the full flow
• Unit tests for registry, invocation, parameter validation, and result handling
• Clear error handling for: tool not found, invalid parameters, execution failure

Technical Decisions

• JSON Schema vs Pydantic for tool parameter definitions
• Sync vs async tool execution (recommend async-first with sync wrapper)

Dependencies

None — this is the foundation for all tool work.

Design Spec Reference

Section 11.1, 11.2 — Tool System Architecture