Read graph context and exact graph facts. Actions: guide, ontology, ontology_conformance, schema, ontology_search, metadata, entity, state, history, transitions, why. schema reads active ontology/SHACL bundle metadata without running validation. ontology_conformance serves the durable report referenced by the pinned published root. entity returns one node's metadata, scalar attributes, bounded Base-backed edge neighborhood, history, and observations. Use lbb_query with SPARQL property paths for precise path selection.

Analytical and expert reads. Modes: structured (SPARQL-subset JSON body), sparql (SPARQL text), analyze. SPARQL is the only query surface. Relations are https://littlebigbrain.com/r/NAME and types https://littlebigbrain.com/class/NAME (both lowercased); entities are content-addressed, so anchor a named one by its rdfs:label rather than building its IRI. Structured and text queries pin one published watermark for the request.

Read model-training inputs or compare retrieval configurations over one pinned published snapshot. shadow_eval takes the API ShadowEvalRequest body; dataset actions return bounded training examples at an optional signal split.

Write graph facts, retract them, or label ranked results. mode=facts writes triplets/embeddings/properties; mode=retract removes a wrongly-added fact (by edge or by entity) without a full reset; mode=search_feedback stores query/result relevance labels (Feedback grades: 3=ideal/good, 1=partial, 0=bad; include query, search_id when available, target, rank, score). Explicit idempotency_key wins; when omitted, MCP derives a stable content hash so content-identical retries dedupe. Facts mode defaults edge_idempotency to append; pass skip_unchanged for re-runnable backfills.

Mutate stored graph configuration. Actions: define_ontology, evolve_ontology, and publish_schema. Schema publication atomically activates metadata and enqueues durable conformance; it never validates the whole graph in the request.

Branch lifecycle. Actions: create (fork a new branch off from_branch — the tool's branch argument names the NEW branch) and merge (validate-then-merge: replay from_branch's post-fork commits onto the scoped target branch — its fork parent — as ONE commit with event ids preserved; SHACL-validates the would-be merged state first and refuses with the report on violations; a fact superseded on the target after the fork wins over the branch's version, reported as a supersedure_race conflict; delete_source consumes the merged branch).

Remember a conversation: store the turns verbatim as an EPISODE evidence entity, then anchor + gate the supplied facts on an observe branch (LLM extraction cannot poison the main graph). Facts with both endpoints already in the graph are anchored; unanchored facts need confidence >= 0.8 to mint new entities, else they come back needs_review. auto_merge merges the branch onto the scoped branch when SHACL validation is clean (the validate-then-merge). Server flag-gated (--enable-observe). This build takes caller-extracted facts (each with a structured triplet); bare statements come back needs_review.