Book a shipping label (seller)

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

Annotations declare destructive=true and readOnly=false, and the description adds substantial context beyond them: state transition to dispatched, cost deducted from payout, idempotent retry safety, the 501 labels_coming_soon behavior before launch, and the GLONGUS_API_KEY requirement. That is exactly the extra behavioral detail annotations cannot carry.

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?

Front-loaded with the action and required input, then each following sentence adds a distinct operational fact (state change, cost, retry safety, launch status, auth). No filler.

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 two-parameter mutation with no output schema, the description covers the return value (label_url for printing), the failure mode (501 until live), and auth requirements. An agent has everything needed to invoke and handle results correctly.

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 0%, so the description must compensate. It explains where rate_id comes from (get_shipping_rates) but says nothing about transaction_id beyond its presence, leaving its txn_ prefix/identity semantics to the schema pattern alone.

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 and resource ('Buy the label for a rate_id'), plus the exact downstream effect ('moves the sale to dispatched'). It names get_shipping_rates as the source of rate_id, distinguishing it from that sibling without opening either schema.

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 routes the agent to get_shipping_rates first to obtain rate_id, which is the key precondition. It does not state when-not to use it (e.g., versus mark_dispatched for handover sales), so a small gap remains.

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