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

Adds substantial context beyond the annotations: 503 semantics for upstream failure and exhausted daily capacity (uncharged), the $0.01/call x402/card pricing model, the fact that repeated calls are billed again, and Brave's terms forbidding storage, resale, or model training. The annotation set already covers read-only/non-destructive/open-world, and the description layers billing and failure behavior on top - exactly what an agent needs before calling a paid endpoint.

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-loaded with what the tool does and returns, with pricing and failure semantics pushed later where they belong. It is dense and somewhat packed into two long sentences, but no clause is filler - each adds return shape, terms, cost, or failure behavior.

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?

Despite having no output schema, the description covers return fields, result-count limits, failure status codes, billing, licensing restrictions, and the natural next tool. For a paid open-world search endpoint, nothing an agent needs to call it correctly or interpret the result is missing.

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% (q max 400 chars, count 1-20 default 10), so the schema already carries the parameter burden and the baseline is 3. The description adds slight value by restating the 1-20 result bound and giving a worked query example ('q=x402 payment protocol') that models the expected query syntax.

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 and resource ('Search the web and get the top results as JSON') and immediately enumerates the returned fields (title, URL, snippet, page age) plus the backing provider (Brave Search API). This distinguishes it from siblings like news, papers, wikipedia and extract, which the agent can rule out 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?

Gives an explicit usage condition ('Use when an agent needs current information or sources from the open web') and a concrete follow-on route ('Pair with /extract to read a result in full'), which routes the agent correctly between sibling tools. It does not explicitly state when to prefer news, papers or wikipedia over this generic search, so the routing is strong but not fully enumerated.

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