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

Annotations already declare readOnlyHint/idempotentHint/non-destructive, so the safety bar is low, but the description adds real value the annotations don't: USPS pickups are free, so cost only varies for UPS, and nothing is committed. It omits that UPS quotes depend on date/ready_time/close_time/overweight scheduling windows, which are behavioral constraints not spelled out at the top level.

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, twenty words, zero waste. The cost question comes first and the non-binding constraint is front-loaded in the same breath, which is exactly the order an agent needs.

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 10-parameter quote tool with no output schema, the description conveys the essential shape: it returns a price, USPS is free, nothing is committed. It leaves unstated that package_count and total_weight_oz are what actually drive the UPS price and that several parameters are UPS-only, but the schema covers most of that.

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 60% and the description adds no parameter-level meaning beyond implying that carrier choice drives whether the quote is zero. The carrier/date/close_time/ready_time/overweight descriptions live in the schema, not the prose, so the description neither compensates for the uncovered location, package_count, and total_weight_oz params nor restates what is already there.

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?

Names a specific resource (USPS/UPS pickup) and a specific question answered (what it would cost), and immediately distinguishes itself from a booking tool with 'Nothing is booked.' An agent can tell this apart from schedule_pickup 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?

'Nothing is booked' makes the non-committal, pre-purchase role of this tool explicit, which is the key routing decision versus schedule_pickup. It stops short of naming that sibling or stating the expected sequence (quote, then schedule), so the guidance is clear but not fully explicit.

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