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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety needs no restating. The description adds real behavioral context beyond them: per-day granularity and the counting semantics (units left; for moorage, feet free and longest boat that fits). It stops short of noting limits such as max range or pagination, so it is not a full 5.

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, no filler, and the capability statement is front-loaded before the alternative routing. The first sentence is dense with parentheticals, which costs a little readability, but nothing is wasted.

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, the description need not explain return shape, and it covers scope, counting semantics, and routing. Minor ambiguity remains around products where nothing is 'counted' and around the boatLengthFt requirement, but overall it is sufficient to call the tool 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 coverage is 100%, so the baseline is 3. The description goes beyond the schema by explaining what the counts mean per product type and by tying the moorage case ('feet free and the longest boat that fits') to the otherwise thin boatLengthFt parameter.

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?

The description states a concrete operation (day-by-day availability across a date range) plus what is returned per day, and explicitly distinguishes itself from the sibling quote_trip. An agent can tell immediately that this is the range/calendar tool, not the point-quote tool.

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?

It names the alternative (quote_trip) and the exact condition that selects it: a yes/no on exact dates plus a unit count. The day-by-day-between-two-dates framing defines the condition for using this tool by contrast, so routing is unambiguous.

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