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

Annotations already declare readOnlyHint=true and openWorldHint=true, covering the safety profile. The description adds useful behavioral context: Weight/Dimensions default to the order's stored values, packages must use the same carrier, and the [DEMO] tag hints at operational status. It does not discuss rate response format or potential external API delays, but with the output schema present and read-only annotation, the additional info is sufficient.

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 two sentences and front-loaded with the main purpose. It packs essential requirements and a key default behavior without verbosity. The [DEMO] tag is a minor extra but does not hurt clarity. Every word contributes.

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?

Given the tool's complexity (6 parameters, nested objects) and the rich input schema (100% coverage) plus output schema, the description is concise but sufficient. It covers the primary use case and critical behaviors, and the structured schemas fill in the rest. It lacks explicit guidance on alternatives, but that is already addressed in usage guidelines. Overall, it is complete for an agent to invoke correctly in most situations.

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%, so the baseline is 3. The description adds value by summarizing the required parameters and clarifying the defaulting behavior for Weight and Dimensions, which reinforces the schema but also helps the agent identify the core requirements at a glance. The 'From' parameter's dual nature (address or profile) is also echoed. This elevates it above the baseline.

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 starts with a specific verb and resource: 'Get shipping rates for an existing Teapplix order.' This clearly distinguishes it from sibling tools like teapplix_get_rates (which likely handles general rate lookups without an order) and teapplix_purchase_label_for_order. The 'existing order' phrasing sets clear scope.

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 states required inputs (TxnId, From, Packages) and explains package requirements, including the carrier consistency rule and the defaulting behavior for Weight/Dimensions. It does not explicitly name alternative tools or state when not to use it, but the 'existing order' qualifier implies that other rate tools are for non-order contexts. Sibling names provide additional context, but this could be more explicit.

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