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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world behavior, so the safety profile is fully covered structurally. The description adds only 'Returns break-even units and revenue,' which slightly overlaps the existing output schema and omits edge cases (e.g. behavior when price per unit does not exceed variable cost).

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 the core purpose in the first sentence and keeps each sentence short. The final pointer to list_bundles is arguably tangential for a computation tool, keeping it just short of perfect.

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 simple read-only calculator with an output schema and full schema parameter coverage, the description covers purpose, inputs, outputs, and navigational context. The remaining gap is edge-case behavior, which the annotations and output schema partly absorb.

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 coverage is 100%, so all three parameters are already documented in the schema. The description merely restates the inputs ('fixed costs, price/unit, variable cost/unit'), adding no formula context such as units, currency, or sign conventions beyond what the schema provides.

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 ('Compute') and resource ('break-even point in units and revenue'), so an agent immediately knows what it produces. However, it doesn't differentiate itself from any sibling calculator beyond the self-evident topic, which is fine given there is no competing break-even tool, but it stops short of the 5-tier sibling-naming example.

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?

Explicitly names the use context ('Use for business plans and pricing decisions'), which exceeds the bare minimum of an implied use. There are no exclusions or alternative calculators named, but for a standalone finance utility the stated context is clear enough.

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