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

Annotations give readOnlyHint=false, openWorldHint=true, destructiveHint=false; the description adds crucial cost behavior: 4 credits, charged only on success, nothing charged when data is empty. It also explains the meaning of the 'winnable' flag (difficulty <=30). That goes beyond the annotations, though it does not cover authentication or rate limits.

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?

Front-loads the main outputs and keeps the cost model at the end. The single dense sentence is packed but readable; each clause carries information, though the list is long and could be slightly trimmed.

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 one-param read-heavy tool with no output schema and annotations covering safety, the description provides an unusually complete picture of the return payload and billing behavior. It lacks explicit when-to-use vs siblings and any mention of rate limits or auth, keeping it below 5.

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?

Schema coverage is 100%, so the schema already documents the single 'topic' parameter (string, 2-200 chars, 'A keyword or a buyer question'). The description reinforces that it is one topic and outlines the returned fields, adding context about what the topic yields, but the parameter itself is fully covered by the schema.

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?

States a specific verb+resource (keyword research) and enumerates the exact outputs: search volume, CPC, difficulty, top 10 Google results, People Also Ask, related ideas, and Perplexity citations. This is unusually specific and distinguishes it from siblings like visibility, search_positions or build_ideas.

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?

The description implies when to use it (for one topic, to find winnable keywords) and gives a selection heuristic ('Pick a winnable idea with real volume over a hard one with more'), but it does not explicitly compare to sibling tools such as build_ideas, visibility, or search_positions. Usage guidance is present but not framed as when-to-use vs alternatives.

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