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

Annotations already declare readOnlyHint=true and openWorldHint=true, and the description adds meaningful behavioral context beyond that: free-call limits, per-call pricing after the limit, in-band payment location, default timespan, data source, and the shape of the sentiment result. It does not discuss failure modes or data-quality limitations, which keeps it from a 5.

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?

The description is compact and front-loads the commercial/payment constraints before explaining the sentiment output and use case. Every sentence contributes, though leading with pricing rather than the tool's core analysis slightly delays the primary purpose.

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?

Given the simple three-parameter schema, existing output schema, and annotations, the description covers purpose, data source, default window, result fields, cost, and use case. It is complete enough to invoke correctly, with the main missing piece being explicit sibling differentiation.

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 q, lang, and timespan. The description adds the default window of 7 days for timespan and clarifies that q can be a topic, company, or person, but it does not add substantial semantics beyond 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?

The description states a specific analyzed resource: average tone of worldwide news coverage about a topic/company/person over a window, with label, trend, and timeline, sourced from GDELT DOC 2.0. This is clear enough to distinguish it from generic search or entity-extraction siblings, though it does not explicitly contrast itself with news_monitor or news_entity.

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 an explicit use case: judging whether coverage of a topic is negative or positive and whether the trend is improving or worsening. It does not state when not to use it or name alternative sibling tools for overlapping news workflows, so it is clear but not fully routing-oriented.

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