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

The description adds useful behavioral detail beyond the annotations by stating that it ranks by absolute percent change, returns signed pct_change, and includes an up/down/flat direction. Since annotations already declare read-only, idempotent, and non-destructive behavior, the description's extra computation and output semantics are valuable and consistent.

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 description is three concise sentences with no filler. The core selection logic is front-loaded, and the return-format note plus the briefing context each add useful information without redundancy.

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 simple read-only tool with all parameters optional and sensible defaults, the description covers what is ranked, over what window, and what is returned. Minor gaps remain around basket semantics and exact response format, but the tool is callable without additional clarification.

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 0%, and the description does not define top_n, basket, or horizon_days explicitly; it only echoes 'Top N' and 'lookback window.' The basket enum values and defaults are left entirely to the schema, so the description does not compensate for the missing parameter documentation.

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 clearly identifies a specific analytical resource: top N FX pairs ranked by absolute percentage change over a lookback window, and it names the output fields. It does not, however, explicitly distinguish it from sibling tools like fx_volatility_leaders or fx_strength, so it stops short of full differentiation.

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 'Daily/weekly market briefing' hints at the intended use case, and 'lookback window' loosely connects to horizon_days. No explicit when-to-use or when-not-to-use guidance is given relative to the many sibling FX tools, so usage is only implied.

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