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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds the concrete endpoint GET /properties/carriers, which confirms a static reference lookup, but says nothing about response size, caching, or stability of the carrier list. Useful but modest value on top of annotations.

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?

One front-loaded sentence stating the resource, the contents, and the consumer use, followed by the endpoint. No filler and nothing requiring the reader to hold context across sentences.

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 zero parameters, no output schema, and annotations carrying the safety profile, the description covers everything needed to call it correctly: what it returns, what those values feed into, and the underlying route. Nothing an agent needs is missing.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The description correctly makes no parameter claims that could mislead.

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?

Specific verb (list) plus resource (carriers) and an enumeration of the payload: shipment services/modes and billing codes. An agent can immediately distinguish this from extensiv_list_facilities or extensiv_list_items because the description names the exact domain objects returned.

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 clause 'the values an order's routingInfo and billingCode must use' tells the agent this is a prerequisite lookup before extensiv_create_order, which is real usage context. It stops short of naming the sibling or stating exclusions, so it is clear context without explicit alternatives.

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