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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds valuable context beyond that: no API key needed, the no-data error behavior instead of returning a stale price, and what the return includes (unit and market location). It stops short of describing report freshness windows or rate behavior, but for a stored-report lookup this is strong.

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?

Front-loads purpose and sibling differentiation, then layers behavioral detail. Five sentences are dense but each earns its place except for mild redundancy around the current-quote vs history distinction, which is stated twice.

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?

Even without an output schema, the description covers the return shape (most recent price, unit, market location) and the failure mode (no-data error rather than stale price). Combined with annotations and full schema coverage, an agent has everything needed to call it 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?

Schema description coverage is 100%, with both parameters documented and an enum for product, so the schema carries the parameter burden. The description reinforces that the pair is commodity/state and that geography must come from a tracked MARS report, but adds no syntax or format detail beyond the schema. Baseline 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?

States a specific verb and resource (latest cash grain price for one commodity in one state) and names the data source (USDA MARS daily market reports). It explicitly distinguishes itself from get_grain_history by describing the sibling as the same series extended over time.

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?

Gives explicit when-to-use guidance ('Use for a current quote') and names the alternative with its selecting condition ('use get_grain_history instead for trends across days'). The current-quote vs trend distinction is exactly what an agent needs to choose between the two.

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