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

Annotations only give readOnly=false, openWorld=true, destructive=false. The description adds substantial behavior beyond them: carrier availability/fees, default per-call confirmation (and that it can be disabled for this tool), the 'reaches other people, confirm with the user' side effect, and the API key requirement.

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?

The operational facts are front-loaded and every sentence carries information, though the 'like Schedule a Pickup' phrasing and the confirmation sentence are slightly wordier than needed. Still efficient overall.

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 booking/mutation tool with no output schema, the description covers cost, availability, prerequisite lookup, confirmation behavior, side effects, and auth needs. Nothing an agent needs to call it correctly 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?

Schema coverage is 100%, so the schema already documents all five parameters including carrier enum and the USPS-only total_weight_oz. The description adds carrier-level context (USPS vs UPS handling) but no per-parameter syntax or format detail beyond the schema, so the baseline 3 applies.

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?

States a specific verb and resource ('Ask USPS or UPS to collect your packages') and distinguishes the two carriers it routes between. It also names get_account_balance as a prerequisite, separating it from sibling read tools.

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 covers carrier-specific usage: USPS is free and runs daily except Sunday, UPS is requested by hand and fee-bearing, so check get_account_balance first. It also states the human-confirmation requirement before each call.

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