MCP

Reliability

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Add it to any MCP client that supports remote servers.

{
  "mcpServers": {
    "mcp-234": {
      "type": "http",
      "url": "https://datadef.io/mcp"
    }
  }
}

39 tools

• get_design_guide

  When: read once before your first canvas_* call, to build or to edit. Datadef's standard for a readable diagram (size, edge discipline, nested zones, notes) and the tool workflow: which canvas_* tool to use when, batching, laying out once, checking with canvas_view. It is the…

• canvas_describe_canvas

  When: Use when you want a flat list of every node, edge and zone. canvas_view shows the same ids as a zone tree with positions and defects, and is usually the better first read. Get an overview of the current canvas: zones as a nested tree in reading order, every node with its…

• canvas_inspect_nodes

  When: Use before changing a node's fields or columns, to see everything it carries: columns, metadata, owners, neighbours. Get full detail for specific nodes: all columns with types and keys, metadata, schedule, formula, owners. Use before modifying a node so you preserve…

• canvas_search_icons

  When: Use before adding nodes that should show a vendor logo (Snowflake, Kafka, Power BI) and you are unsure of the icon id. Find icon ids in Datadef's library (2000+ cloud and data-tool logos) by product name, e.g. "Amazon Aurora PostgreSQL", "k8s", "Azure Event Hubs". Pass…

• canvas_measure_canvas

  When: Use only for a precise manual placement the user asked for: exact x/y/width/height per node. To check a layout, canvas_view is faster and already reports overlaps. Get exact geometry: every node's position and size in canvas units, the overall canvas bounds, and any nodes…

• canvas_add_nodes

  When: Use to add components (tables, pipelines, sources, consumers, service icons), each placed in its zone with `group`. Add one or more nodes to the canvas. Batch every node you want in a single call. Positions are assigned by canvas_layout_canvas afterwards — never set them…

• canvas_add_standalone_node

  When: Use only when the user wants a node at a specific position, outside the automatic layout. Otherwise use canvas_add_nodes. Add a single data node at an exact position, without connecting it to anything. Use when the user wants something placed somewhere specific, or when…

• canvas_update_nodes

  When: Use for any in-place change: rename a node or zone (it keeps its size and contents), edit a note's text, recolour (`color: "green"`, `fill`, `family`), change a zone's style, swap an icon, or change a data node's type; fields you do not pass stay as they are. Many nodes in…

• canvas_replace_node

  When: Use when one component changes identity or type (Redshift becomes Snowflake, a card becomes a service icon). The node keeps its id, connections, lineage, zone, position and fields. Turn a node into a different component in place — Redshift becomes Snowflake, a batch job…

• canvas_remove_nodes

  When: Use to delete nodes and their edges. Removing a zone keeps its contents (they move up to the parent, same place on screen): that is how to ungroup. Pass keepChildren:false only to delete the zone with everything inside it. Delete nodes, notes or zones, with every edge and…

• canvas_connect_nodes

  When: Use to draw the flows that genuinely move data between two nodes. Never connect a zone: connect a node inside it. Draw edges (arrows) between nodes to show how data flows. Label an edge only when the reader could not guess what it does ("CDC", "hourly batch"); obvious…

• canvas_update_edges

  When: Use to relabel, retype, restyle (dashed, colour), reverse, put arrowheads on both ends, or re-point an existing edge, instead of disconnecting and reconnecting it. Change existing connections in place: relabel, retype, restyle (solid/dashed/dotted, colour), reverse the…

• canvas_disconnect_nodes

  When: Use to delete specific edges between two nodes. Remove edges, given as source and target, or as an edge id / "Source -> Target" string in `edge`. Batch: `edges` takes a list; put every item in one call rather than one call per item. Operates on one Datadef diagram…

• canvas_set_columns

  When: Use `mode: "merge"` to add or update (renameTo) a few columns, `mode: "remove"` to drop some, or the default replace for the full list. Columns that stay keep their ids and lineage. Change a table's columns. mode "merge" adds new columns and updates (or renames, with…

• canvas_group_nodes

  When: Use to create a zone (a layer, domain, stage or boundary), nested with `parentGroup`, optionally moving existing nodes into it: the zone is drawn around them where they are, inside the zone they already share. Create a labelled zone (e.g. "Bronze Layer", "Ingestion") and…

• canvas_move_to_group

  When: Use to move existing nodes or zones into another zone (they are placed inside it and the zone grows to fit), or out of every zone with group null. A zone cannot move into its own sub-zone. Move existing nodes or zones into an existing zone, or out of every zone (group…

• canvas_add_lineage

  When: Use to record which source columns produce which target columns. No line is drawn. Record column-level lineage: which source column produces which target column, and how. This is what makes the diagram queryable for impact analysis, so add it for every real…

• canvas_remove_lineage

  When: Use to delete lineage rows between two nodes (one column pair, or all rows between them). Lineage pointing at deleted nodes or columns is cleaned automatically. Delete lineage rows between two nodes: one column pair, or every row between the two nodes when no column is…

• canvas_add_text

  When: Use for a note that tells the diagram's reader a decision, constraint or gotcha. Pass `anchor` (the node or zone it explains) and it is placed beside it, no coordinates needed. To edit a note's text use canvas_update_nodes. Add a text note: a caption, a callout, a note…

• canvas_add_shape

  When: Use rarely: a pointer or highlight the user asked for. Never as a backdrop; zones are the containers. Place a rectangle, circle, arrow, or line as a visual annotation — a divider, a highlight. Shapes are drawings: they connect nothing (use canvas_connect_nodes for arrows…

• canvas_add_flow_arrow

  When: Use after the final layout, where one arrow should stand for a bundle of identical flows (zone to zone). Draw one large labelled arrow SHAPE between two areas of the diagram — "ingest", "serve", "publish". It is a drawing, not a connection: it links nothing and moves with…

• canvas_add_region

  When: Use after the final layout to mark nodes that belong together without moving them into a zone. Regions do not move with layout. Draw a labelled translucent area behind existing nodes to show they belong together, without reparenting them. Use this when the grouping is a…

• canvas_suggest_simplifications

  When: Use when the diagram feels dense or the user asks to simplify. It changes nothing; it reports what could collapse. Report where this canvas could be collapsed — groups of similar nodes that could become one summary node — without changing anything. Use it to decide…

• canvas_collapse_nodes

  When: Use to merge several similar nodes into one while keeping their connections, usually after canvas_suggest_simplifications. Merge several nodes into one summary node, keeping every connection. Use when a set of near-identical objects adds length without adding meaning…

• canvas_move_nodes

  When: Use only when the user asked for a specific placement. Moving a zone moves its children; never move the children as well. Set node positions precisely. Use absolute x/y to place something exactly, or dx/dy to nudge it. Coordinates are absolute canvas units (same space…

• canvas_resize_nodes

  When: Use only when the user asked for a specific size. Set the width and height of nodes. Mostly for shapes, text boxes, and group zones — data nodes size themselves from their content, and resizing one can clip what it displays. Batch: `resizes` (up to 40) takes a list; put…

• canvas_align_nodes

  When: Use only when the user asked for alignment that layout does not give. Align nodes to a shared edge or centre line, or space them evenly. Cleaner and far more reliable than computing coordinates by hand. Batch: `nodes` (up to 40) takes a list; put every item in one call…

• canvas_layout_canvas

  When: Use once, after the structure (zones, nodes, edges) is complete, not after each change. With no arguments it only places what was added or changed; nothing else moves. Set mode "full", direction (LR/TB/RL), spacing (compact/normal/airy), fit…

• canvas_validate_canvas

  When: Use before you finish: broken references and icons, nodes outside their zone, overlapping zones or nodes. Loops are reported as information only. Check your work: broken references, broken icons, nodes sticking out of their zone, overlapping zones or nodes, unconnected or…

• canvas_view

  When: use to see a diagram before you edit it and after each round of changes; this is how you check your work. It answers in milliseconds from the saved diagram, where export_diagram starts a browser for 6-10 s. Returns a text map: the zones as a tree, each with its place on a…

• canvas_batch

  When: use whenever you would otherwise make several canvas_* write calls in a row, above all with tools that take one item per call: create every zone (group_nodes), convert many nodes (replace_node), set several tables' columns (set_columns). Eighteen zone creations or…

• create_diagram

  When: use when Datadef's own model should design a whole new diagram from a description or a pasted schema. To build it yourself step by step, use create_blank_diagram; to change an existing diagram, canvas_view and the canvas_* tools, or edit_diagram. Generates a professional…

• create_blank_diagram

  When: use when you will build the diagram yourself with the canvas_* tools, because you want control over the result or already know the architecture from the conversation. Use create_diagram instead when Datadef's model should design the whole thing from a prompt. Creates an…

• list_diagrams

  When: use to find the id of an existing diagram before viewing, editing or exporting it. Lists the diagrams in the user's Datadef account, most recently updated first. Next: canvas_view with the diagram_id to see it.

• get_diagram

  When: use to show the user a diagram (it attaches a rendered PNG and a markdown image line, 6-10 s), or to poll a diagram that create_diagram or edit_diagram is still working on. To check your own edits, canvas_view is faster and reports overlaps. Returns every node with its…

• edit_diagram

  When: use for a large change you can describe in words better than you can make it tool by tool: "reorganise this into bronze, silver and gold", "rebuild the consumption side from this spec", "add owners and schedules everywhere". For a precise change (rename, add a node, rewire…

• export_diagram

  When: use to give the user an image of a diagram, or a link to download, attach or embed one. Not to check your own edits: a render starts a browser (6-10 s), while canvas_view answers in milliseconds and reports overlaps. Renders a diagram to PNG or JPEG. Returns the image…

• repo_status

  For a diagram that was created from a connected git repository: which repo and branch or tag it tracks, when it last synced, the commit it reflects, and whether daily sync is on. Use repo_refresh to sync it now. Only the owner of the repository connection can use this.

• repo_refresh

  Re-sync a repo-linked diagram from the current state of its repository. If the tracked branch or tag has not moved since the last sync, nothing changes. If it has, the diagram is REGENERATED from the repository, which replaces manual canvas edits. Only the owner of the…

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