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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds the from/to-vs-timespan mutual exclusion and the shape of metric output, but both of those are also spelled out in the schema, so the net behavioral value beyond structured fields is modest. No auth, rate-limit, or result-size context is given.

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?

Three tight sentences, all front-loaded: purpose first, then metric semantics, then the two routing constraints. No filler and nothing repeated unnecessarily.

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 9 parameters, full schema coverage and an output schema present, the description only needs to frame purpose, metric choice, and the time-window rule — all of which it does. Return format is legitimately delegated to the output schema.

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 every parameter including metric values and the from/to vs timespan constraint. The description restates the metric choices compactly but adds no syntax or format detail the schema lacks; baseline 3 is appropriate.

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 ('Return GDELT global-news timeline series for required `query`') and immediately scopes it against siblings by naming the shared operator syntax with gdelt_search and pointing tone work at gdelt_tonechart. An agent can distinguish it from gdelt_search/gdelt_context without opening a 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?

Explicitly routes one case away to a sibling ('use gdelt_tonechart for a tone histogram') and states the timespan vs from/to exclusivity, both actionable selection rules. It stops short of saying when to prefer this timeline over gdelt_search for the same query, so it is strong but not fully exhaustive.

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