Select nodes

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds real behavioral context beyond that: a side effect (nodes on another page switch the editor to that page first) and an explicit reassurance that it 'changes no design data.' This discloses a viewport/page-changing behavior the annotations do not.

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?

Three tight sentences, front-loaded with purpose before the mode details and behavioral caveats. No filler; every clause carries information an agent needs (intent, mode semantics, side effect, safety).

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 selection tool with no output schema, the definition covers purpose, mode behavior, page-switch side effect, and non-mutation assurance well. It does not state what the call returns (e.g., resulting selection state), a minor gap given no output schema exists.

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 75%, with nodeId/nodeIds/session already described. The description adds genuine value for `mode` by stating its allowed values and the default ('replace (default)'), which the schema enum does not convey on its own. This is meaningfully beyond the structured data.

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 states a specific verb+resource ('Select nodes on the canvas') and even the intent behind it ('so the user sees exactly what you mean or are about to change'), clearly marking it as a UI-affordance tool distinct from mutators. It does not explicitly name the read-counterpart sibling (figma_get_selection) or other alternatives, so it falls just short of a 5.

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?

It gives clear situational context for when to reach for this tool – pointing the user at the nodes you mean or are about to change. There are no explicit exclusions or named alternatives (e.g., 'use figma_get_selection to read, this to set'), so it stops short of 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.