Create an isolated Play Session. Hosted creation requires authentication and is saved by default; local stdio creation lasts for the server process.

Resume an accessible Play Session and return its persistence status, current projection, unresolved inputs, and relevant next operations.

Return the agent-facing workflow guide, accepted fill shapes, result paths, supported intent aliases, and recovery rules for this MCP.

List every installed redistributable SRD Stat Block with ids, authored names, ordered procedure summaries (including retained text-only entries), attacks, defenses, and damage modifiers. Catalog presence does not imply that every source is executable in every workflow.

List every installed redistributable SRD Unit id grouped by kind. This reports catalog presence only; legal and executable sources still come from the consuming workflow's canonical discovery result.

Return the canonical installed redistributable SRD Unit record as unitRecordJson for one catalog id. Parse that JSON for the complete authored detail; catalog detail is not a claim of source executability in any particular workflow.

Begin creating a character in this Play Session by storing a new draft and returning its draftId, unanswered creation choices, revision, and finalization status. Continue with fill_creation_holes, then finalize_character when ready; use discover_creation_holes to resume an existing draft. Omitting draftId creates a new draft on each call; an id already used by a draft or finalized character is rejected.

Return the current supported fillable creation holes, draft revision, and finalization status for a stored character draft. Every returned choice option is admitted by this server's active execution support profile.

Submit an atomic batch of creation fills for a stored draft using option ids returned by its current holes. Accepted batches replace the stored draft; rejected batches leave it unchanged.

Finalize a complete supported character draft. A ready finalization stores the resulting in-play record by characterId and removes the active draft. Druid Wild Shape drafts require selected known Beast Stat Block ids.

Update a finalized character outside Battle: change equipment or levels, manage forms and companions, apply healing or rests, advance recovery time, or spend and convert resources. Choose one operation.kind and its matching fields; every affected Character Session must be available in this Play Session. Returns character state and, when applicable, an operation result; calendar-time recovery may request dice fills. Changes can consume resources and are not safe to repeat blindly. Use query_character_session for read-only projections, creation tools for drafts, and Battle tools for in-Battle actions.

List all finalized characters in this Play Session, including characterId, Battle availability, and build-derived facts. Available rows include mutable sheet state, current and maximum HP, Hit Dice, spell slots, Pact Slots, and feature resources; characters in Battle are marked unavailable, and unfinished drafts are excluded. Use a returned characterId with inspect_character_session for stored details or query_character_session for a calculated projection.

Inspect one selected Character Session as its canonical stored session plus core build-derived Hit Point, Hit Dice, Spell Slot, Pact Slot, and resource facts.

Read one calculated result for a finalized character outside Battle without changing its state. Choose query.kind for ability-check abilities or jump abilities, proficiency, linked speeds, Armor Class, spell access, known forms, rituals, or Weapon Mastery, and supply only that variant's fields. The character must be available in this Play Session. Use inspect_character_session for stored character and core sheet facts, or apply_character_session_operation to change it.

Select an SRD Stat Block for the battle session. This stores only the Stat Block id in the MCP session.

Start a battle session from finalized Character Builds and selected SRD Stat Blocks. When list_stat_blocks exposes alternative Sizes, provide one authored size on that Stat Block combatant. The caller must provide Initiative scores for every combatant; choose initialSetup to keep the SDK-owned Initiative setup open for the battle_lifecycle surface.

Apply one Battle lifecycle operation: swap Initiative with a willing ally or finalize initial setup, or atomically add/remove a supported Character Session or installed Stat Block combatant while the Battle is active.

Return the current battle-runtime checkpoint/frontier envelope and MCP session summary.

Read the Battle's current checkpoint/frontier and available acts without changing state. Call after start_battle or any Battle mutation to learn whether setup, pending holes, or executable acts are present; copy a returned subject exactly into resolve_battle_act when initialHoles is empty, otherwise use fill_battle_hole. If the frontier contains pending holes or an interrupt decision, finish it before choosing another act. Returns the same envelope as read_battle_state.

Fill one hole for a selected battle act subject. MCP retains the base session, subject, and accepted fills while the battle runtime advances the checkpoint/frontier envelope.

Execute a currently available Battle act whose initialHoles is empty, using its exact subject from discover_battle_acts. This requires an active Battle with no pending fills; use fill_battle_hole for acts that require input. The operation applies the act's effects and resource costs, stores the updated Battle, and may return further required input or reactions. Do not repeat a successful call blindly; creatureFalls also accepts table-supplied reactionSpellTargetFacts.

End the current combatant's turn in an active Battle after all pending fills are resolved. Use actorId for the current actor in the returned Battle state. The operation applies end-of-turn effects and stores the result; the response may require hole fills or reaction decisions before play advances. Continue from the returned frontier with fill_battle_hole when required. Use end_battle to finish the entire Battle.

Finalize the stored battle session and hand character-owned post-battle facts, including current HP, back to durable character session state.

Sample an ordered, non-empty batch of structured dice groups with deterministic non-cryptographic DRDice and return visible raw faces. Each call advances the Play Session's dice sequence. This independent sampler never reads Battle Holes, derives modifiers or outcomes, or fills a Hole; copy its faces into an ordinary typed fill only when the current runtime Hole supplies the required facts.