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

Annotations (readOnlyHint=true, destructiveHint=false, idempotentHint=true) already indicate a read-only, safe operation. The description adds no behavioral context beyond annotations, such as pagination, caching, or rate limits. This is acceptable given the low risk indicated by 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?

Two sentences with zero fluff. Every word adds value: listing carriers, their ID/codes, and the use case for rate comparison.

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 list tool with an output schema, the description is complete. It covers the purpose, output constituents, and use case. Annotations provide safety profile, so no further behavioral detail is needed.

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% for the single optional 'filter' parameter. The description adds example values (e.g., 'ups', 'usps') but essentially restates the schema's description. With high coverage, the baseline is 3.

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 verb 'List' and the resource 'connected shipping carriers' with explicit outputs (IDs and codes) and examples (USPS, UPS, FedEx, DHL). It differentiates from siblings like logistics.shipengine.rates and logistics.shipengine.validate.

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 rate comparison ('Shows which carriers are available for rate comparison') but does not explicitly state when to use this tool versus alternatives like logistics.shipengine.rates or logistics.shipengine.validate. No direct comparison or exclusions.

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