Retrieve a rendered widget's current state, including the user's selection or click and reported values, plus unmapped edited files for livemaps.
Read a widget back, including selection: what the human clicked (table row, chart bar) or what an MCP App reported. For livemaps, unmappedFiles lists edited files no node covers (time to update the map).
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations exist, so the description carries the full burden, and it does disclose part of the return surface: `selection` and the livemap-specific `unmappedFiles`. However, it says nothing about error behavior (unknown id), side effects, or freshness, and no output schema exists to fill that gap.
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 tight sentences, front-loaded with the core action before the return-value details. The livemap aside is niche but short and actionable, though the backtick-heavy phrasing is slightly dense.
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 one-parameter read tool with no output schema and no annotations, the description partially compensates by naming key return fields. It still leaves the id semantics and failure modes undocumented, so an agent can call it but not fully anticipate the result.
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?
The single required `id` parameter has 0% schema description coverage, and the description never explains what the id refers to or its format. Since the parameter count is low the baseline is generous, but the description adds essentially no meaning beyond the schema.
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+resource ('Read a widget back') that clearly contrasts with the write-oriented siblings place_widget, update_widget and remove_widget. It never names a sibling explicitly, so differentiation is inferred from read-vs-write semantics 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?
Usage is implied by the return-content framing ('what the human clicked'), which tells the agent this is how you learn about user interaction, but there is no explicit when-to-use versus read_canvas or when-not-to-use guidance. An agent must infer the routing from the verb.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.