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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context: it compares published aggregates only, does not recommend trades, and returns provenance. It also notes the CIT exception in the schema (combined only), which is a meaningful behavioral constraint 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?

The description is compact and front-loaded: the first sentence states the core function and constraints, the second lists return values, the third gives example queries, and the fourth clarifies limitations. Every sentence earns its place with no 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 read-only comparison tool with 100% schema coverage and no output schema, the description is nearly complete. It covers what the tool does, what it returns, example usage, and a limitation. The only minor gap is that it doesn't explicitly state what happens if fewer than two or more than eight markets are provided, but the schema's 'Two to eight' constraint covers that.

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 100%, so the schema already documents all five parameters. The description adds value by clarifying the markets parameter ('Two to eight exact CFTC contract codes or unambiguous names') and the report_type parameter ('Categories differ by family; use search or the evidence pack to discover available families'). It also explains the scope default and CIT exception, which goes beyond the schema.

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 states a specific verb ('Compare'), a precise resource ('latest reported CFTC COT position'), and a clear scope ('two to eight contract markets using one consistent report family, scope, and trader category'). It also names the return values (stable market codes, exact dates, long/short/net positions, open interest, ranking, provenance), which distinguishes it from sibling tools like cftc_cot_latest and cftc_cot_history.

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 gives explicit example queries ('compare managed-money positioning in oil, gold, and copper' or 'which selected market has the largest commercial net position?') and states what it does not do ('does not recommend trades'). It also implies when to use it versus siblings by emphasizing comparison across multiple markets, and the schema notes to use search or the evidence pack to discover available families.

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