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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered; the description adds a concrete cost model ($0.004 per query) and notes results are returned 'as the engine ranks them', which is real operational context. It stops short of stating history retention limits or whether history ignores the search-only parameters.

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?

Three compact clauses: capability first, mode routing second, alternative and cost last. Every sentence carries decision-relevant information and there is no filler.

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 10-parameter read-only tool with no output schema, the description gives capability, modes, sibling alternative and pricing, which is enough to call it correctly. The main residual gap is the odd interaction between required `query` and action=history, plus no hint at result shape or pagination.

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 all ten parameters are already documented, including the search/history action semantics the description restates. The description adds no format guidance (country vs. language interaction, page vs. num_results, or why `query` is required even for action=history), so the schema is doing the heavy lifting.

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?

Names a specific verb and resource (structured search-engine results: organic listings, ads, related data) and enumerates the supported engines (Google, Bing, DuckDuckGo), plus it splits the two modes the single tool serves. An agent can distinguish it from alterlab_search and alterlab_news without opening any schema.

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?

Explicitly routes between modes ('action=search (default) to run a query, or action=history to read earlier SERP queries for your account') and names the alternative with its selecting condition ('prefer alterlab_search when you also want each result page read'). Nothing 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.