Multi-Commodity Market Brief

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

Beyond readOnlyHint and openWorldHint annotations, the description discloses API key requirement (OILPRICEAPI_KEY), request counting ('counts as 1 request'), per-account code limits, and that the API response is authoritative. It also explains the narrative option adds plain-English context with disruptions and indicators. No contradiction with 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 well-structured, front-loading the purpose and scope, then usage guidance, then the optional narrative parameter, then requirements and alternatives. It is slightly dense, but every sentence contributes valuable routing or invocation information.

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 tool with no output schema, the description lists what the brief includes (spot prices, 24h changes, forecasts, spreads) and clearly notes the narrative option, API key requirement, request cost, and limits. It is sufficiently complete for an agent to select and call the tool, though exact response structure is not detailed.

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?

Input schema coverage is 100%, so the baseline is 3. The description adds some clarity about natural language vs. API codes and the narrative behavior, but these mostly overlap with the schema's own descriptions. It does not meaningfully extend parameter meaning beyond 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 opens with a specific verb and resource: 'Get a multi-commodity market brief: latest spot prices, 24h changes, 1-month forecasts... for several commodities in ONE call.' It clearly distinguishes this tool from siblings by explicitly contrasting it with opa_get_price and opa_create_price_subscription.

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 states exactly when to use it: 'Use when the user wants a market snapshot, morning brief, or an at-a-glance read across multiple commodities.' It also gives alternatives — 'For a single price use opa_get_price; for ongoing recurring monitoring use opa_create_price_subscription' — so the agent can route correctly.

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