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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered. The description still adds non-obvious behavior: results are ranked as on the Threads page and each entry aggregates multiple stories, plus pagination via cursor and the 72h default window. It stops short of describing return shape or rate limits.

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 that lead with the resource and its ranking, then the optional filters, then sibling routing. No filler, though the parenthetical examples make it slightly denser than strictly necessary.

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 still conveys what a returned item represents (a storyline grouping many stories around one event) and its ordering. Combined with 100% schema coverage and rich annotations, an agent has everything needed to call it correctly.

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 all four parameters (limit, topic, cursor, window) are already documented with defaults and accepted formats. The description only echoes 'optionally one topic or a time window' and adds no syntax, format, or interaction detail beyond the schema. Baseline 3 applies.

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 resource ('The storylines Mappit is following worldwide'), the ranking semantics, and what each item contains ('Each groups many stories about one developing event'), with concrete examples. An agent can distinguish this listing tool from get_thread (one storyline) 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 to alternatives: 'Use get_thread for one storyline's stories and Mappit's analysis; whats_happening gives the storylines around one place.' That names both the when-to-use and the when-to-use-something-else conditions.

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