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

With no annotations, the description carries the full burden and delivers. It explains the FRED+ETF bridging mechanism, spot_basis variants, fallback to etf_share_price, and warns not to claim $/oz when basis is etf_share_price. It also discloses staleness flags and the meaning of live_basis arithmetic. This is highly transparent about the tool's behavior and quirks.

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 quite long, but it is front-loaded with the core purpose and usage rules, and the subsequent field-by-field breakdown is necessary given the absence of an output schema. It could be split into clearer sections, but every sentence serves a functional purpose.

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?

Since there is no output schema, the description meticulously documents all response fields, their meanings, and example values (e.g., live_basis format). It also covers symbol behavior and fallback scenarios, making the description fully self-contained for an agent to invoke the tool and interpret its result correctly.

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?

Despite 0% schema description coverage, the description explicitly explains the 'symbol' parameter: 'symbol=oil returns both WTI and Brent; default all returns all six.' This adds crucial meaning beyond the bare enum, telling the agent the effective default and grouped behavior for 'oil'.

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 'REAL-TIME spot prices for the macro commodities (oil WTI/Brent, gold, silver, nat-gas, copper)', which is a specific verb+resource statement. It further declares itself the 'AUTHORITATIVE source for any numeric commodity claim', distinguishing it from any potential price-related 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?

Explicit guidance is provided: 'call this BEFORE quoting a price level', 'QUOTE spot DIRECTLY', and for 'official_close' only if the user explicitly asks for the last settlement/closing price. This tells the agent exactly when and how to use the tool, including what to quote.

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