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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds real context beyond that: the payload fields returned (long, short, spreading, net, changes, percentages, open interest, source ids, provenance), the bounded nature of the history, the enforcement of report-family categories, and a 'not trading advice' caveat. No auth or rate-limit detail, but that is a minor gap given annotation coverage.

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?

Three sentences, front-loaded with the core verb and resource, then payload contents, then usage examples. The middle field-list is somewhat dense but each item is informative. No filler or repetition of the title.

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?

With no output schema, the description correctly takes on the burden of describing the return payload (net, open interest, provenance, pagination). Combined with 100% schema coverage and annotations covering safety, an agent has nearly everything needed; only explicit sibling routing 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 description coverage is 100% across 9 parameters, so the schema already documents market, report_type, category, scope, limit/offset, dates and response_format in detail. The description restates the filtering dimensions in prose ('report family, scope, and trader category') without adding syntax or format guidance beyond the schema, so the baseline of 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 gives a specific verb and resource: 'Return a bounded weekly history for one CFTC contract market, report family, scope, and trader category.' The time-series framing implicitly separates it from cftc_cot_latest and cftc_cot_compare, but neither sibling is named, so an agent must infer the boundary from the tool names alone.

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?

Concrete use cases are supplied ('managed money net positions in crude oil over time', 'commercial gold COT history', 'a reproducible positioning chart'), which clearly signals when this tool applies. However, there is no explicit when-not or routing statement toward cftc_cot_latest/compare/search, so the agent gets context but no exclusions.

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