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

Annotations only cover read-only/open-world/idempotent, but the description goes well beyond them: primary vs fallback source behavior, source named in the response, 404-and-not-charged on empty results, per-call pricing, and the PaymentRequired flow when called unpaid. That is exactly the operational context an agent needs before invoking a paid 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?

Front-loaded with the primary use case and dense throughout – pricing, fallback, and error behavior all earn their place. It is a single run-on paragraph with stacked parentheticals, which slightly hurts scannability but not content value.

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 two-parameter tool with no output schema, the description covers ordering of results, source fallback, failure semantics, and billing, leaving no ambiguity about what happens on invocation.

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 baseline is 3; the description adds value by enumerating example lang values (en, de, fr, es, ja) beyond the schema's generic 'two-letter language code', though it adds nothing new for q.

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 states a specific verb+resource (returns search autocomplete suggestions) and explicitly positions it against the sibling tools by naming /v1/web and /v1/news as downstream consumers. An agent can distinguish suggest from web/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?

It gives concrete use cases (keyword research, SEO ideas, query expansion, topic guessing) and explicitly states where it fits relative to alternatives ('before /v1/web or /v1/news'), so the when-to-use decision is unambiguous.

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