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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavioral context by disclosing usage-based billing with a default request estimate ($0.012 USD) and noting that account-specific pricing may differ, but it says nothing beyond that about the call itself.

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 core sentence is front-loaded and wastes no words. The appended pricing block is template boilerplate but carries real information (cost estimate), so it earns its place, though it visually interrupts the definition.

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 an existing output schema, the description does not need to explain return values, and annotations cover the read-only/idempotent safety profile. Combined with the pricing disclosure, this is nearly complete, with the only gap being the absence of explicit guidance on when to call it versus its many siblings.

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 for the description to clarify. Baseline 4 applies, and nothing in the text misrepresents the (empty) input surface.

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 specific verb and resource: it returns the list of Google languages supported in the App Data API. This clearly distinguishes it from the similarly-named Apple sibling (get_dataforseo_app_apple_languages) by naming the platform, though it does not explicitly call out the sibling or the related google_locations endpoint.

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 only implied: an agent infers this is a reference-lookup endpoint for enumerating valid Google language values before calling other App Data tools. There is no explicit when-to-use statement, no mention of alternatives like the Apple or locations endpoints, and no prerequisites.

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