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

The description adds behavioral details beyond the annotations by stating it is deterministic and does not save, send, or create. This aligns with the readOnlyHint and destructiveHint=false annotations. However, it does not disclose potential error conditions or failure modes.

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 a single, concise sentence that front-loads the primary action. It avoids unnecessary detail and is well-structured.

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?

The description lacks information about the output format or what the preview contains (e.g., breakdown, totals). It also does not explain edge cases like empty items or invalid coupon codes. Given the complexity of the input schema, this leaves gaps in understanding the tool's full behavior.

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 only 29%, and the description does not explain the meaning or expected values of most parameters. It only mentions 'items' and 'customer_id' in the schema, but the description text itself does not elaborate on parameter usage, leaving ambiguity for parameters like tax_mode, coupon_code, and discounts.

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 clearly states the tool's function: it calculates a deterministic estimate preview. It explicitly specifies what it does not do (saving, sending, creating), distinguishing it from other preview tools. The verb 'calculates' and resource 'estimate preview' are specific.

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?

The description implies usage for previewing without committing, but it does not explicitly state when to use this tool versus alternatives such as preview-invoice or preview-broadcast-campaign. There is no explicit guidance on when not to use it.

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