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 useful extras — CSV download of the full list and a last-updated date (2026-04-06) — but says nothing about response format or whether the list is cached/static. Comparable in weight to a scope-only addition, so a 3.

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 substantive sentences: what you get, plus the CSV alternative and freshness date. The opening clause restates the obvious ('You will receive the list of languages') and the pricing boilerplate is injected noise, but the payload is compact overall.

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 zero-parameter, read-only lookup with an output schema present, the description covers purpose and an alternate retrieval channel (CSV) plus data freshness. Nothing needed to invoke it correctly is missing; the only gap is which downstream call consumes the returned language codes.

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 nothing to document; baseline 4 applies. The description correctly implies a no-argument retrieval.

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 resource (the list of supported Baidu SERP languages) and the name pins the engine and data type, so it is distinguishable from sibling endpoints like get_dataforseo_serp_baidu_locations or get_dataforseo_serp_bing_languages. The phrasing 'You will receive... by calling this API' is slightly passive and never explicitly contrasts with those siblings, keeping it short of a 5.

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?

There is no when-to-use guidance, no note that this endpoint should be called to obtain language codes before submitting Baidu SERP tasks, and no routing to the alternative endpoints (e.g., baidu_locations for location codes). Usage can only be inferred from the tool name.

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