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MCP Tools for C4 Diagrams

The C4 Diagrams group lets an AI assistant review your C4 Diagram Sets and C4 Diagrams and work on them: find missing diagrams, check coverage, and add or change nodes, boundaries, and connectors. It is the only group of the MCP Endpoint whose delete tools are permanent.

  • ✅ 38 tools: 15 read, 18 write, 5 delete
  • ✅ Coverage, impact, and missing-diagram reviews of a whole set
  • ✅ Two scopes for changes: one to create, one to modify and delete

The group is not selected by default in the AI Assistant: it has 38 tools, and the default selection already holds 108, so you untick other tools first (Choose Your Tools). The MCP Tool Reference explains the OAuth scopes, the paging rules, and the other groups.

Understanding the Scopes in This Group

Scope Tools
mcp:repository.read The 15 read tools
mcp:c4diagrams.create c4_create_set, c4_create_diagram, c4_clone_diagram
mcp:c4diagrams.modify The other 20 write and delete tools

Warning

c4_delete_diagram permanently deletes a diagram with all its boundaries, nodes, and connectors, and c4_delete_set permanently deletes a set. Neither can be undone. Grant mcp:c4diagrams.modify only to users who may do that. c4_detach_custom_metadata, c4_remove_diagram_tag, and c4_replace_diagram_tags remove links too, but MCP clients don't see them flagged as destructive.

c4_list_diagrams and c4_list_sets return 25 items by default, at most 200.

Review Tools (15)

Tool What it does
c4_get_diagram_custom_metadata The Custom Metadata values attached to a C4 diagram
c4_get_diagram_header The raw model of one C4 diagram
c4_get_diagram_tags The Tags attached to a C4 diagram
c4_get_set One C4 Diagram Set by its id
c4_list_available_custom_metadata_definitions The Custom Metadata definitions available to C4 diagrams
c4_list_diagrams C4 diagram headers, to support write workflows
c4_list_sets C4 Diagram Sets
compare_c4_diagrams_by_scope Compares the diagrams in a set by scope, grouped by System or Service
explain_c4_diagram_context One diagram explained: structure, set membership, scope, and improvement suggestions
get_c4_diagram_coverage_matrix The coverage matrix of a set, per element and rule
get_c4_diagram_entity_usage Which entities are used across all diagrams in a set
get_c4_diagram_set_overview A set's diagrams with coverage and suggestion summaries
get_c4_impact_review The impact records of a set
get_c4_missing_diagram_candidates Diagrams that may be missing from a set
get_c4_related_entity_candidates Related entities that could be added to a diagram

Create and Change Tools (18)

Tool Scope What it does
c4_create_set create Creates a C4 Diagram Set
c4_create_diagram create Creates a C4 diagram header
c4_clone_diagram create Clones a diagram into the same set, with its boundaries, nodes, and connectors; Tags and Custom Metadata are not copied
c4_add_boundary modify Adds a boundary to a diagram
c4_add_connector modify Adds a connector to a diagram
c4_add_node modify Adds a node to a diagram
c4_add_diagram_tag modify Attaches an existing Tag to a diagram
c4_attach_custom_metadata modify Attaches an existing Custom Metadata value to a diagram
c4_detach_custom_metadata modify Unlinks a Custom Metadata value from a diagram; the definition stays
c4_link_article_to_node modify Links an Article, Snippet, or Template, by slug, to a node
c4_promote_diagram modify Promotes a Draft diagram to Active
c4_remove_diagram_tag modify Unlinks a Tag from a diagram; the Tag stays
c4_replace_diagram_tags modify Replaces a diagram's whole Tag list in one step
c4_update_boundary modify Updates selected fields of a boundary
c4_update_connector modify Updates selected fields of a connector
c4_update_diagram modify Updates a diagram header
c4_update_node modify Updates selected fields of a node
c4_update_set modify Changes a set's name or description

Delete Tools (5)

All five need mcp:c4diagrams.modify and are permanent.

Tool What it deletes
c4_delete_boundary A boundary from a diagram
c4_delete_connector A connector from a diagram
c4_delete_node A node from a diagram
c4_delete_diagram A diagram, with all its boundaries, nodes, and connectors
c4_delete_set A C4 Diagram Set

Next Steps