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

Annotations already declare the safe read-only, idempotent, closed-world profile, and the description goes further: it discloses the return content (each driver's ordered stops with miles and minutes), failure handling (names addresses it could not place), and a hard constraint (US addresses only). That is meaningful behavioral context beyond the annotations.

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 tightly packed sentences, front-loaded with what the tool does and its limits, with no filler. Dense but every clause (driver count, address cap, output shape, US-only caveat) earns its place.

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 no output schema, the description compensates by describing the return format and the unplaced-address case, and it flags the geographic constraint. For a 5-parameter planning tool with full schema coverage and annotations, nothing an agent needs to invoke 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% and every parameter already has a written description, including the goal enum. The description only restates the limits (25 stops, optional start, optional return), so it adds little beyond what the schema provides – the baseline 3 is appropriate.

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 (plans/optimizes the driving order of delivery addresses) and pins down the scope precisely: one driver or up to 5, up to 25 US addresses, optional start and return. An agent knows exactly what the tool produces without opening the 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?

States the target user and intent ('anyone with several stops... who wants the fastest order or a fair split between drivers') and draws a boundary ('does not give turn by turn directions'). Clear context, though there are no sibling tools to route between, so no explicit alternatives are needed.

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