Ship a parcel (buy label)

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

Annotations already indicate destructiveHint=true. Description adds critical context: 'THIS CHARGES YOUR BALANCE', asynchronous delivery, and retrieval method. No contradiction with 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?

Three concise sentences, each adding essential information. No filler, front-loaded with the main action. Every sentence earns its place.

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 moderate complexity and good schema/annotations, the description covers prerequisites, action outcome, async behavior, and post-action retrieval. Slightly more detail on rate_id source could elevate completeness, but it's already adequate.

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% and already describes both parameters. Description adds no new semantic meaning beyond the schema, merely reiterating the confirm=true requirement. Baseline 3 is appropriate.

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?

Description clearly states the verb 'Purchase a parcel label' and identifies the specific resource (parcel label) and prerequisite (rate_id from deftship_get_parcel_rates). It distinguishes the tool from siblings by referencing related tools for rates and retrieval.

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 states when to use (after getting rates) and requires confirm=true. Mentions alternative retrieval via deftship_get_parcel. Does not fully elaborate on when not to use or compare to batch shipping, but provides sufficient guidance.

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