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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds genuinely useful behavioral context that annotations do not: this is a paid call at $0.01 and the output is not trade signals. It still omits pagination, result-count behavior, and whether FNG is embedded per row or as a summary.

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 short fragments with the price front-loaded and no filler; every clause carries information. The telegraphic style costs some clarity ('FNG' is unexpanded), but nothing is wasted.

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?

There is no output schema to explain the return shape, so the description must carry it, and it does not describe the response structure, how the FNG overlay is attached, or how many markets come back. Combined with the unaddressed limit parameter and the unexplained 'movers' framing, an agent cannot confidently predict the result.

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 only 50%: api_key is well documented in the schema, but limit has no description anywhere. The description says results are ranked 'by 24h volume' but never explains what limit controls, its default, or its maximum. With low coverage the description should compensate for the undocumented parameter and does not.

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 says it returns Polymarket public markets ranked by 24h volume with a Fear & Greed overlay, which is concrete content. But the tool name promises 'movers' (i.e., odds changes), which the description never mentions, and it does not distinguish itself from nearby siblings such as odds_pulse, odds_history, or free_odds_sample. An agent knows roughly what data comes back but not what 'movers' means here.

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?

'Not trade signals' is a disclaimer, not usage guidance. There is no statement of when to call this versus the free sample, history, pulse, or hypothesis siblings, and no prerequisites beyond the pricing note. The agent must infer the use case from the name alone.

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