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

Annotations already declare readOnly, idempotent, non-destructive, and open-world. Description adds rich behavioral context: it returns all carrier scan events with timestamps and locations, delivery milestones, transit days, and origin/destination countries. It also lists support for 3,200+ carriers across 220 countries. No contradictions.

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?

Description consists of two dense sentences with zero wasted words. The first sentence packs multiple relevant details, and the second provides an essential prerequisite. No redundancy or fluff.

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 single parameter, presence of an output schema, and annotations covering safety/idempotence, the description is fully adequate. It explains what the tool returns and the necessary precondition, leaving no critical gaps for agent understanding.

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?

Input schema has 100% coverage with a clear description of the tracking_number parameter. The tool description adds value by elaborating on the output fields (timeline, events, milestones) and the prerequisite of registration, slightly surpassing the baseline 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?

Description clearly states it retrieves full tracking timeline, including latest status, carrier scan events, timestamps, locations, and delivery milestones. It distinguishes from sibling 'logistics.tracking.register' by explicitly noting the package must already be registered, and from 'logistics.tracking.list' by providing detailed event-level data.

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?

Description explicitly states when to use (for a registered package needing full tracking details) and when not (if number not registered, call tracking.register first). This provides clear usage boundaries and an alternative action.

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