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

Annotations declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is already clear. The description adds useful behavioral details: the cost comparison, the DataForSEO envelope structure (data in tasks[0].result, status_code), and the fact that rejected requests still return HTTP 200. These go beyond annotations. However, it does not explain why the tool takes no parameters despite implying a keyword is needed, which is a notable gap in behavior disclosure.

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 structured into three sentences: purpose, return fields, and cost/envelope details. It front-loads the primary action and uses concise bullet-like listing of fields. The cost and envelope details are extra but relevant. The emoji and pricing might be slightly extraneous, but overall it is efficient.

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?

Given the tool has no parameters and an output schema exists, the description should clarify its purpose and usage. However, it contradicts the title (locations vs. ads) and fails to explain how a keyword is specified without parameters. It also does not mention any relationship to the locations family of tools. The description leaves critical gaps about the tool's actual function and invocation context.

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 has zero parameters, so schema coverage is trivially 100%. The description does not need to explain parameters, but it implies a keyword is used ('ads running against a keyword') without indicating how it is supplied. This is misleading given the empty schema. It does list return fields, which adds some value, but the mismatch undermines parameter understanding.

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 verb+resource: 'Returns the ads running against a keyword on Google' and lists the fields returned. However, the tool name and title reference 'locations' for the SERP API, which contradicts the described purpose. This mismatch likely confuses an agent about whether this returns ad results or a location list, and it does not clearly differentiate from siblings like get_dataforseo_serp_gads_advertisers_locations.

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 guidance on when to use this tool versus alternatives. It does not mention any conditions, exclusions, or recommended contexts. The only extra context is cost and response envelope, but nothing about usage scenarios.

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