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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuinely new behavioral information beyond the annotations: that no authentication is required to call it, which matters for an agent operating before sign-up. It stops short of describing response shape, but annotations carry the rest.

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?

A single sentence that front-loads the core purpose and then enumerates covered topics, with no filler. The comma-separated content list is dense but each item maps to a distinct thing an agent might need, so nothing feels wasted.

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?

With no parameters and no output schema, the description must convey what comes back, and it does so by listing the covered subject areas (plans, prices, feature gating, sign-up). For a simple zero-arg informational tool this is close to sufficient; only the response format itself is unstated.

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 is no parameter semantics to document and the baseline of 4 applies. The description correctly avoids inventing inputs the schema does not have.

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 enumerates the specific content the tool returns: what Apptiller does for App Store apps and websites, plans and prices, feature-to-plan mapping, and owner connection/sign-up flow. This is clearly an informational/overview tool, distinguishable from action siblings like start_sign_up or submit_launch, though it never uses an explicit verb like 'Returns' or 'Explains'.

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?

'No sign-in needed' implies it is safe to call before authenticating, which is useful context relative to start_sign_up. However, it never states when to prefer this over free_app_check or browse_launches, nor does it say the tool is the entry point for understanding pricing before signing up; the routing is left to inference.

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