---
title: Design-time capabilities
---

The design-time tools turn a plain-language request into Chronicle artifacts — read models, projections, audits, and catalogs — grounded in the store's real schema. They are read-only against the store and generative against your codebase: nothing is written to the store, and generated code comes back as a proposal you review. See [How it works](/chronicle-mcp/concepts/) for the principle behind them.

## Capabilities

| Capability | Tool | Use it to |
| ---------- | ---- | --------- |
| [Describe an event type](/chronicle-mcp/design-time/describe-event-type/) | `describe_event_type` | Read an event type's real fields and types — the grounding primitive the others build on. |
| [Read-model scaffolding](/chronicle-mcp/design-time/read-model-scaffolding/) | `scaffold_read_model` | Turn a set of event types into a reviewable read model + projection, grounded in their schema. |
| [Unconsumed-event audit](/chronicle-mcp/design-time/unconsumed-event-audit/) | `audit_unconsumed_event_types` | Find events nothing reads, and consumers pointing at event types that no longer exist. |
| [Event catalog](/chronicle-mcp/design-time/event-catalog/) | `generate_event_catalog` | Produce a living data dictionary — every event, its fields, and its consumers. |
| [Causal trace](/chronicle-mcp/design-time/causal-trace/) | `explain_causal_trace` | Turn an event source's raw log into a "what happened and why" narrative. |

## How an agent combines them

A typical flow chains a few tools. To answer *"Show me all the users registered"* an agent might:

1. Resolve candidate event types (`list_event_types`, or [Event catalog](/chronicle-mcp/design-time/event-catalog/)).
2. Inspect their real fields with [describe an event type](/chronicle-mcp/design-time/describe-event-type/).
3. Check whether a projection already answers the question, then propose one with [read-model scaffolding](/chronicle-mcp/design-time/read-model-scaffolding/).

Because the tools return structured data rather than prose, the agent does the natural-language reasoning while the store supplies the facts.

## Roadmap

The [capability hand-off](https://github.com/Cratis/Chronicle.Mcp) sketches ten design-time capabilities. The five above are the grounding-and-generation core. The remaining ideas — missing-event-type suggestions, projection-vs-reducer advice, consistency-boundary (DCB) advice, schema-evolution assistance, spec scaffolding, and constraint suggestions — build on the same introspection pipeline and are candidates for future releases.