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

Annotations already cover the read-only/idempotent/non-destructive profile, so the bar is lower. The description adds genuinely useful behavior beyond the structured fields: 'Worlds never pause' (no pausing means the listing stays current) and the 24-hour activity window, which tells the agent what 'active' means. It does not mention pagination or result caps, hence not 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 purpose is front-loaded correctly and the closing sentence 'Worlds never pause' earns its place. However, the bulk of the text is a long enumeration of returned fields (name, region, pace, years, dates, players, active counts, link) — content an output schema already provides, so much of the sentence is redundant here.

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 an output schema present, return-value detail needn't live in the description, and annotations handle the safety profile; the required context for this tool is mostly covered. The remaining gap is the absence of any guidance on filtering behavior or how this list relates to the sibling get_world.

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 75%, so the schema largely carries the load. The description restates the pace semantics (Standard = 20 minutes, Blitz = 5) that the schema already documents for `type`, and gestures at region and 'open right now' but says nothing about `lang` or the status enum values (RUNNING/FINALE/FINISHED). Marginal added value.

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 and scope: 'Public Jetopolis worlds open right now', which clearly implies a listing operation for live worlds. This is distinguishable from the singular sibling get_world, but the description never names that sibling or explicitly contrasts the two, leaving differentiation to inference.

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?

The phrase 'open right now' implies when the tool is appropriate (browsing live worlds), but there is no explicit when-to-use or when-not-to-use guidance and no reference to get_world or world_standings as alternatives. Usage is suggested rather than stated.

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