canvas_update_edgesChange existing connections without deleting them: fix a label, change the type, or restyle. Use this to correct a wrong edge label rather than disconnecting and reconnecting.
Operates on one Datadef diagram, named by diagram_id.
| Name | Required | Description | Default |
|---|---|---|---|
| updates | Yes | ||
| diagram_id | Yes | Canvas id, from list_diagrams, create_diagram, or create_blank_diagram. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true, and the description adds context by clarifying the operation modifies existing connections in place ('without deleting them') rather than deleting and recreating. It doesn't discuss side effects or permissions, but with annotations present, the additional context is sufficient.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is two sentences, front-loaded with the core purpose and immediately useful examples. Every sentence contributes to understanding the tool's function and usage, with no redundant or wasted text.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a mutation tool with two parameters and no output schema, the description covers the essential aspects: what it does, when to use it, and how it differs from alternatives. It could mention that the operation is destructive (per annotations) more explicitly, but given the schema and annotations, it is adequately complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 50%, with diagram_id and source/target described in the schema. The description compensates by mapping 'fix a label, change the type, or restyle' to the label, type, and style parameters, giving meaning to otherwise undocumented fields. It also implies the updates array structure.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb ('Change existing connections') with a clear resource (connections/edges) and lists concrete actions (fix a label, change the type, or restyle). It distinguishes itself from sibling tools like canvas_disconnect_nodes by explicitly saying 'without deleting them' and contrasting with 'disconnecting and reconnecting'.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides explicit usage guidance: 'Use this to correct a wrong edge label rather than disconnecting and reconnecting.' This gives a clear when-to-use and an alternative approach. It also scopes the operation to a single diagram via diagram_id.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Each tool has a clear, distinct purpose: canvas_add_nodes vs canvas_add_standalone_node, canvas_add_region vs canvas_group_nodes, and canvas_describe_canvas vs canvas_inspect_nodes are all well-differentiated in their descriptions. The only slight overlap is between get_diagram and canvas_describe_canvas, but they operate at different levels (full diagram vs current canvas state).
All canvas tools follow the consistent canvas_verb_noun pattern (e.g., canvas_connect_nodes, canvas_remove_nodes, canvas_layout_canvas), while high-level tools follow verb_noun (create_diagram, export_diagram). The two groups are internally consistent and the prefix clearly separates them.
With 34 tools, the server exceeds the recommended range for a typical MCP server. While every tool has a distinct role, the sheer number of canvas manipulation tools (27) feels heavy for most diagram-editing tasks and could be consolidated without losing functionality.
The tool set covers diagram creation, reading, updating, and export, but there is no delete_diagram tool, breaking the full CRUD lifecycle. Canvas editing is comprehensive, but the missing deletion at the diagram level is a notable gap that agents cannot work around.