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

Annotations already cover readOnly, idempotent, non-destructive and closed-world, so the bar is lower, yet the description still adds real signal: no AI call, no cost, instant return, nothing created or changed, and a returned link that opens the GYSM builder pre-loaded with the prompt. That reveals latency, side-effect and output-shape behavior the annotations cannot express.

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, front-loaded with the verb and the enumerated outputs, then the clarifying constraints. The output list is long but earns its place since no output schema exists; 'creates nothing and changes nothing' slightly overlaps with 'It is a plan, not a generated app'.

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-only tool with no output schema, the description carries the burden of describing returns and does so explicitly by listing the plan components and the builder link. Nothing an agent needs to call it correctly or to know what comes back is missing.

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?

There is a single required parameter with 100% schema description coverage ('What the app should do and who it is for, in plain English (max 600 characters)'). The description only restates it as a 'plain-English app idea' and adds no detail beyond the schema, so the baseline 3 applies.

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 ('Turn ... into a build plan') with a concrete input ('plain-English app idea') and then enumerates the exact artifacts produced: use case, page sections, features, data model, integrations, limits, refined prompt, and builder link. The 'web app' framing also implicitly separates it from the store-oriented sibling plan_online_store, so an agent can pick it 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?

Usage is implied rather than stated: use it when you have an app idea and want a plan instead of a built app. The clause 'It is a plan, not a generated app' draws a useful boundary, but no sibling is named and no when-not condition (e.g., versus compare_ai_app_builders or plan_online_store) is given.

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