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

Annotations only declare readOnly/openWorld/idempotent-false/destructive-false; the description adds substantial context beyond that — per-call cost ($0.01 via x402 USDC or credits key), failed calls free, an explicit warning that repeats are not free (explaining the non-idempotent hint in cost terms), licensing limits on reuse, and hard caps of 10 articles within a day/week/month window. That is unusually rich disclosure for a read-only tool.

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?

It is front-loaded with the capability and output shape, and each subsequent sentence (limits, disclaimer, licensing, use cases, pricing) adds a distinct fact. The single dense paragraph blends pricing and licensing into the middle, which could be ordered better, but there is little waste.

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?

With no output schema, the description carries the burden of describing return values and does so field by field, plus aggregates; it also covers cost, failure pricing, and recency caps. An agent has everything needed to decide and call correctly for a three-parameter tool.

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 description coverage is 100%, so the schema already documents all three parameters including the 1-10 count range and the day/week/month freshness values. The description only restates those ranges and adds an example value (q=bitcoin), so it meets but does not exceed the baseline.

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 names a specific resource (news headlines on a topic) and states exactly what is produced: title, URL, publisher, age, plus a DistilBERT positive/negative score and the balance across articles. That is clearly distinct from the raw `news` sibling, though the alternatives are never named explicitly, so differentiation is inferred rather than stated.

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 for a market mood check, brand monitoring or a news brief" gives concrete use cases, and "Not a market signal" plus "results are for the caller's immediate use only (Brave API terms)" mark boundaries on interpretation and reuse. What is missing is an explicit routing statement telling the agent when to pick `news` or `pack_web_research` instead.

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