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

Annotations already indicate readOnlyHint=false (mutating), openWorldHint=true (external interaction), and idempotentHint=true. The description adds context beyond these: it's FREE and keyless, requires a CONFIDENT match, returns 0 on ambiguous/unknown apps, saves durable URLs on success, and indicates the agent should relay failures plainly. No contradiction with annotations.

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 front-loaded with the core action and usage condition, then expands on parameters, cost, and behaviors. It's dense but every sentence carries essential information; a slight trimming of the 'REAL' emphasis could tighten it, but it remains well-structured and not verbose.

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?

Despite no output schema, the description fully explains the tool's behavior: what it returns on success (durable URLs saved), what happens on failure (0 screens, saves nothing), and how the agent should handle that. It also covers the default parameter behavior and prerequisites (brand with 0–1 screens), making it complete for an agent to decide and execute correctly.

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 input schema already has 100% coverage with descriptive text for appName ('the app's name to look up on the App Store — defaults to the saved brand's name') and brandId ('a brand id/name from list_brands to save the screens onto; omit to use the active brand'). The description re-states the default but adds no new parameter syntax or details, so a baseline 3 is appropriate.

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 clear action with a specific resource: 'Pull an APP brand's REAL App Store screenshots into the workspace brand.' It explicitly mentions the use case with make_template_ad(template:'app-ui-tour') and the user's phrasing, differentiating it from generic asset fetching.

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 explicitly tells when to use: 'Use when the brand has 0–1 app screens on file and you want make_template_ad(template:'app-ui-tour'), or the user asks to pull my app's screenshots.' It also clarifies edge behavior (ambiguous app returns 0 screens) and advises not to retry with guesses, leaving no ambiguity about alternatives.

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