OilPriceAPI

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

With no annotations provided, the description carries the full burden. It effectively discloses return values ('price with 24h changes, plus the spread') and input flexibility ('Accepts natural language or codes'). It lacks mention of potential rate limits, data freshness, or whether the comparison is real-time vs cached.

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?

Four sentences each earning their place: purpose, usage trigger, return values, input format. Front-loaded with the core action and scope. No redundancy or filler.

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 no output schema exists, the description adequately documents return values (prices, 24h changes, spread calculation logic). With 100% schema coverage for the single parameter and clear sibling differentiation, the description is complete for this tool's complexity.

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 has 100% coverage with good examples. The description adds valuable semantic context that the parameter 'Accepts natural language or codes', clarifying that informal names (like 'brent') are valid inputs beyond formal codes, which enhances understanding beyond the schema alone.

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 the specific action ('Compare current prices'), the resource (commodities), and the scope ('between 2-5 commodities side by side'). The mention of 'side by side' and 'spread' clearly distinguishes this multi-commodity tool from siblings like opa_get_price which likely returns single prices.

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?

Provides explicit when-to-use guidance with concrete examples ('Use when the user asks to compare commodities (e.g., 'Brent vs WTI', 'US gas vs EU gas')'). However, it lacks explicit 'when not to use' guidance or naming of alternatives (e.g., opa_get_price for single commodities), which prevents a 5.

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