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

Annotations already cover safety (readOnly, non-destructive, open-world, non-idempotent), yet the description adds genuinely new behavioral facts: $0.01 per call via x402 USDC or a card key, failed calls are free, and repeated calls are not free. It also discloses a licensing constraint ('results are for immediate use only (Brave API terms)') that no structured field conveys.

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 purpose, then usage, then cost and constraints in a single dense block. The opening clause largely repeats the title, which is minor waste, but the pricing and licensing sentences each carry real information.

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 three-parameter search tool with no output schema, the description covers result fields, result cap, freshness options, cost model, failure pricing, a licensing restriction and a usage example. Nothing an agent needs before calling it 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%, so 'q', 'count' and 'freshness' are already documented in the schema. The description restates the 1-20 range and the day/week/month freshness options and adds only a sample query value, which is marginal added meaning over 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 (news search) and names the underlying source ('Brave news index') along with returned fields. It does not explicitly distinguish itself from close siblings like 'news', 'feed' or 'pack_news_sentiment', so an agent must infer the boundary, but the operation itself is unambiguous.

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?

'Use when an agent needs the latest news or headlines on a company, coin, person or event' gives a concrete usage context plus a worked example (q=bitcoin ETF). There is no explicit when-not guidance or named alternative tool, which keeps it below a 5.

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