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

With no annotations, the description carries the full burden and does add real behavioral context: it is a GET endpoint, costs $0.04 via x402, and links to docs. It also discloses the output shape (ranking metric + volume surge ratios). It does not mention pagination or whether results are cached/delayed, but the cost and auth model disclosure is substantive.

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?

Front-loaded with the core purpose, then mechanism, then the HTTP/pricing metadata in a clearly delimited bracket. Every sentence earns its place; minor redundancy in restating the /v1/movers shape reference.

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?

No output schema exists, so the description should describe the return payload. It gestures at this ('ranked by absolute probability change... with volume surge ratios') but never enumerates fields, and the unexplained category param undercuts completeness even for a simple 4-param tool.

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 only 25% (just min_liquidity). The description restates the window values '1h/6h/24h' verbatim from the enum, adding no new meaning, and says nothing about limit (default 20, max 50) or why a category parameter exists on a tool already pre-filtered to entertainment. That last point is an unexplained redundancy the description should resolve.

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+resource: markets ranked by absolute probability change, scoped to entertainment. It explicitly distances itself from siblings with 'pre-filtered to entertainment markets' and 'same shape as /v1/movers', so an agent can separate it from probability_movers_crypto, probability_movers_climate, etc. 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?

'The fastest way to see where news is landing in entertainment' implies a use case, and the reference to /v1/movers gives a structural hint. However, no explicit alternatives or when-not conditions are stated, and the sibling set (probability_board_entertainment, probability_calendar_entertainment) is not addressed.

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