Get Refining & Trading Spreads

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

The annotations already mark the operation as read-only and open-world, lowering the bar. The description adds meaningful context by warning that an eligible account entitlement is required and that the API response is authoritative, which are non-obvious behavioral traits not visible in the schema or 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: core purpose up front, followed by usage triggers, then access caveat and alternative. Every sentence earns its place and the structure is front-loaded for an agent scanning for relevance.

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 single-parameter read-only tool, the description covers purpose, semantics, triggers, access requirements, and where to route access/pricing questions. The only minor gap is that it does not describe the response shape, but with no output schema present, the phrase 'API response is authoritative' partially compensates and the scope is clearly bounded.

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% and the parameter is a single enum with descriptions. The description still adds value by expanding each enum value into more concrete domain meaning: crack as refining margin proxy, basis as regional/grade price differential, and margin as blending/transport margin. This goes beyond merely restating the enum names.

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 opens with a specific verb-resource pair — 'Get refining and trading spreads' — and then enumerates the exact categories: crack spreads, basis spreads, and blending/transport margins, with clarifying glosses like '3-2-1 crack' and 'regional price differentials.' This makes the tool's scope unmistakable and distinguishes it from price or market-overview siblings.

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?

It explicitly lists trigger phrasings ('crack spreads, 3-2-1 crack, refining margins, basis differentials, or blend/transport margins') and tells the agent to use opa_get_plans for access/pricing questions, with the API response as the authority. This is clear when-to-use and alternative routing, leaving little to inference.

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