Modify an existing widget's data on the canvas. By default, only the provided keys are shallow-merged; set merge:false to replace the entire data.
Update an existing widget. data is shallow-merged into the current data by default (send only the keys you change, e.g. {edges} on a livemap); pass merge:false to replace it entirely.
| Name | Required | Description | Default |
|---|---|---|---|
| h | No | ||
| w | No | ||
| id | Yes | ||
| data | No | ||
| merge | No | ||
| title | No |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It does disclose a genuinely important behavioral trait — that `data` is shallow-merged by default and fully replaced with merge:false — which is exactly the kind of semantics an agent needs. However it says nothing about permissions, error behavior for a missing id, or whether omitted geometry fields (h/w/title) are preserved.
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?
Two sentences with no filler, and the default behavior (shallow merge) is front-loaded ahead of the override. The {edges} example is compact and earns its place by making the merge semantics concrete.
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?
No annotations and no output schema, so the description is the only behavioral source. It covers the highest-risk ambiguity (merge vs replace) well, but leaves permission requirements and the outcome of updating a non-existent widget unexplained for a mutation tool.
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 description coverage is 0% across 6 parameters, so the description must compensate. It does well on the two non-obvious params, explaining `data` merge semantics with a concrete {edges} example and clarifying `merge:false`; id/title/h/w are left to self-evident naming and get no explanation.
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?
States a specific verb and resource ('Update an existing widget'), which cleanly separates it from place_widget and remove_widget in the sibling list. It does not explicitly name place_widget as the create-side alternative, so sibling differentiation is implicit rather than stated.
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 frames the tool as updating an *existing* widget, which implies it should be used only after the widget exists, but it never says when to prefer place_widget or what to do if the id is unknown. Usage is implied by the verb and the merge discussion, not stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.