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

Annotations cover safety (readOnly, idempotent, openWorld), and the description adds genuinely non-structured context: cost ($0.005/call), a free quota (100 calls/day), the scoring model (direction −1/0/+1, confidence 0..1, horizon), and the tradable_now / next_open fields. That is real behavioral disclosure beyond the annotations.

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 purpose and use cases, then filters, then pricing; minimal waste. The dense parenthetical enumerations of event kinds and impact fields make it long, but each clause carries information an agent needs.

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 an 8-parameter, zero-required read tool with no output schema, the description supplies the return shape, filtering defaults, cost/rate limits, and sibling routing. Nothing an agent needs to call it correctly is missing.

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 the baseline is 3; the description still adds usage-level semantics by framing universe=["NVDA","BTC"] with min_confidence≥0.4 as the configuration for acting, and by tying `since` to backtesting. Some of this (past `since`) restates the schema, so it falls short of full compensation.

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 and resource ('List market-moving events since a point in time'), enumerates the event kinds covered, and describes the per-asset scored output shape. It explicitly differentiates itself from siblings impact_for (one asset's scored impacts) and brief (one-call asset summary).

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 concrete when-to-use scenarios ('what happened in the last N hours that affects my book'), a backtesting case with a past `since`, and explicit alternatives with their selecting conditions (impact_for, brief). It also names the default filter that makes results actionable.

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