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

Annotations already declare readOnlyHint/idempotentHint/openWorldHint, so safety is covered; the description adds genuinely useful behavior beyond that: prices are live, three named service tiers plus the vehicle are returned, and no booking side effect occurs. It stops short of noting rate limits, caching, or what happens with out-of-area addresses.

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 sentences, front-loaded with what the tool does and what it returns, then routing. The 'since 1976' clause and the street address/URL are lightly promotional, though the phone/URL routing is actionable for non-account callers.

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?

With an output schema present, return values need not be enumerated, yet the description still previews them (service tiers, vehicle). It covers purpose, side-effect profile, and the handoff path for a 13-parameter quote tool, leaving nothing an agent needs to call it 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 100% across 13 params, so the schema already carries full parameter meaning; the baseline of 3 applies. The description adds no parameter-level detail (e.g. it never mentions that 'when' drives after-hours pricing or how vehicle/weight interact).

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 verb and resource ('Price a same-day courier delivery'), scopes it geographically (Chicago area) and names the provider. It is immediately distinguishable from sibling book_delivery, which it also explicitly references.

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?

States the boundary condition outright ('Quotes only - nothing is booked') and routes the caller: account-holder agents should use book_delivery, everyone else calls a phone number or visits a URL. Explicit when-to-use and when-not-to-use-plus-alternative.

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