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

Annotations already indicate readOnly, idempotent, not destructive. The description adds value by detailing exact return fields (open interest, long/short/net for three categories, changes) and notes 'Keyless', implying no pagination. No contradictions with 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?

The description is concise (two sentences plus a data listing) with no wasted words. It is front-loaded with purpose, and every sentence earns its place by clarifying usage, parameter format, or return content.

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?

Given the tool's simplicity (single parameter, no output schema), the description adequately covers context. Annotations provide safety profile, and the description explains what data is returned. Minor gap: no mention of potential rate limits or data frequency beyond 'weekly', but overall sufficient.

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% with a clear description of market_name. The description repeats the schema instructions and adds an example, but doesn't provide additional semantic meaning beyond what the schema already offers. Baseline 3 is appropriate.

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 states the tool returns the most recent weekly COT positioning for one futures market. It specifies the resource (COT positioning) and action (retrieve latest), and distinguishes from siblings like report_history by explicitly mentioning 'most recent' and referencing search_markets.

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 description provides clear when-to-use guidance: for the latest COT data. It instructs to pass exact market names from search_markets with examples. While it doesn't explicitly mention when not to use or list alternatives (e.g., report_history for historical data), the context is sufficient for correct selection.

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