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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description still adds real context beyond them: the computation is deterministic, no data is fetched or silently defaulted, the caller must supply compatible series values, and the result is an unsigned replayable receipt. The only gap is that it does not say what the receipt contains or how errors surface, which the output schema likely covers.

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 first two sentences are dense but front-loaded and high-value. The trailing procedural sentences ('Put tool fields inside inputs... Follow its required fields and exact choices. Do not pass the REST calculator field...') are guardrails against wrapper misuse and partly redundant with each other and with the schema, which dilutes an otherwise efficient description.

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?

With an output schema present, the description need not document return values, and it still characterizes the receipt as unsigned and replayable. Both modes, the prerequisite lookup step and the nesting convention are covered, which is enough for a two-branch calculator. The unexplained empty 'units' object and the absent guidance on which branch to pick when both could apply are the remaining gaps.

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 only 33%, so the description has to carry weight, and it does map the two oneOf branches to their semantic inputs in prose. It also flags the nesting ('Put tool fields inside inputs') and warns against passing a REST calculator field, which is genuinely useful. However, it never explains the odd top-level 'units' object (empty properties, additionalProperties false) or the modelVersion enum value, leaving part of the schema opaque.

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 names both deterministic methods with specific inputs and outputs: index-adjusted budget/wage comparison (base amount, base/current index) and agricultural sale net contribution, gross revenue, margin and break-even price (quantity, price, costs, transport, fees). That is a concrete verb+resource statement despite the vague tool name. It differentiates from the lookup siblings by stating 'No data is fetched or silently selected; use the lookup tools first,' though it never names a specific alternative tool.

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 gives an explicit ordering constraint – run the lookup tools first, then preserve source dates and choose compatible values – which tells the agent when this tool is the right second step. It also scopes optional fields ('Supply units or modelVersion only when listed in inputSchema'). It stops short of stating when not to use it or naming a concrete sibling, so it is not a 5.

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