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

With no annotations, the description carries the full burden, and it does disclose real behavioral traits: a 15-minute staleness floor, free pricing via x402, and the HTTP verb. However it omits return shape, pagination/limit behavior, and rate limits, so it is only partially complete for a data-retrieval tool.

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 purpose with the delayed/free constraint stated early, and no filler sentences. The bracketed HTTP/metadata block is slightly dense but compact and earns its place as operational info.

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?

For a 5-parameter tool with no annotations and no output schema, the description covers purpose, freshness, and cost adequately, but leaves the parameter semantics and return/limit behavior under-specified. Adequate at the top level, with clear gaps below.

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 40%, so the description is expected to compensate, but it only echoes the window values ('over the chosen window') and does not explain segment vs category override semantics, min_liquidity, or limit. Most parameter meaning remains undocumented in both places.

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+scope: 'Markets with the largest probability moves over 1h/6h/24h', ranked by 'absolute blended-probability change', with volume surge ratios. It also distinguishes itself from the realtime sibling by name ('identical shape to /v1/movers'), so an agent can tell them apart without opening either 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?

Gives clear usage context ('fastest way for an agent to find where news is landing') and an explicit routing rule: 'Use the paid endpoint for realtime data.' It does not spell out when staleness is unacceptable beyond the realtime alternative, but the free/delayed vs paid/realtime tradeoff is explicit.

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