Open any app

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

Annotations already declare readOnlyHint=true and openWorldHint=false. The description adds useful behavioral context by framing the result as an 'interactive widget,' noting immediate availability for recently saved apps, and comparing against dedicated open_<name> tools. It does not contradict the annotations, though it could elaborate on what an interactive widget entails.

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 compact—three sentences, each earning its place: purpose, usage/alternative, and preference. It front-loads the core action and keeps supporting information tightly relevant.

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?

Given the tool's simplicity (2 params, output schema available, read-only annotations), the description covers the essential context: purpose, usage scenario, timing, and a best practice for reuse. The output schema handles return-value details, so no further description is needed.

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 100% for both parameters, so the schema carries the parameter details. The description reinforces that the app parameter names a registry app and hints at collection binding via the reuse guidance, but does not add substantial new meaning beyond the structured 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?

The description opens with a specific verb-resource pairing: 'Open ANY app from the registry by name as an interactive widget.' It immediately distinguishes from data_list ('no UI') and dedicated open_<name> tools, making the tool's role unambiguous.

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?

Explicitly states when to use the tool ('when the user wants to SEE or OPERATE the data') and identifies the alternative for reading facts (data_list). It also gives timing guidance (works immediately for recently saved apps vs dedicated tools that may take a while) and a reuse preference for collections.

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