Use trace_get_index_health to check the index, then trace_search to find symbols before reading whole files. Use trace_get_symbol for an exact definition and trace_get_outline for file structure. Use trace_get_project_memo at the start of a task when prior decisions matter, trace_query_decisions for a focused recall query, and trace_remember_decision to record an explicit English-language decision with the current bb thread as its session ID. Automatic decision capture rejects non-English text; for a manually entered decision in another language use the panel or bb trace remember. For other capabilities, search the catalog with trace_tools and pass the selected tool name and arguments to trace_call.
The thread's Trace context panel shows index health, saved decisions, and the provider's context-window usage. The same data and explicit writes are available through bb trace status, bb trace decisions, bb trace remember, and bb trace index; pass --thread <id> outside a bb thread.
The plugin runs trace-mcp in the bb environment's repository on its host machine. A thread needs an environment with a path. On first use, indexing may take time. Tool results are capped; narrow or page a query when a result says it was shortened.