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

Annotations already declare readOnly, idempotent, non-destructive, and non-open-world, so the safety profile is covered. The description adds real value beyond that by clarifying this is an advisory planning step to run before writing code and by summarizing what it returns (how to settle with the user, how Control Plane keeps files/records/secrets/replicas, with the relevant tools).

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?

Front-loaded with the core condition (plan before writing when the app keeps state), which is the most important information. However it carries two lengthy example lists that could be trimmed without losing meaning, adding modest verbosity.

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 no-input advisory tool with an output schema present, the description gives enough: when to invoke it, what class of app it targets, and the nature of the guidance returned. Return-value detail is appropriately left to the output schema.

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 tool takes zero parameters, so there are no parameter semantics to document; the baseline for a parameterless tool is 4. The description correctly introduces no input arguments, consistent with the empty 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 (plan) and resource (an app) and precisely scopes it to apps that keep state (content, records, files, sign-ins). It cleanly separates this tool from the direct-build path for stateless apps, so an agent can route without opening the schema.

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?

Gives explicit when-to-use conditions (app persists anything: added/changed content, records, files, sign-ins) and explicit when-not conditions (stateless apps like a game, calculator, or landing page, which should be built directly). Both sides of the decision are named.

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