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

Annotations already declare readOnly/idempotent/non-open-world, and the description adds genuine extra context: execution is 'pure rules and Decimal, no network, model or clock,' cost figures are public city planning numbers rather than quotes, some scope is returned unpriced, and consumption draws on a shared free daily allowance. That is well beyond what the annotations convey and sets correct expectations about determinism and accuracy.

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?

Front-loads the purpose and the fit/cost split in the first sentence, then layers caveats compactly. Slightly dense telegraphic phrasing ('Pure rules and Decimal, no network, model or clock') costs a point, but nothing is redundant.

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 8 all-optional params and no output schema, the description does the work of summarizing the return surface (footprints, fit in both orientations, cost cards, unpriced scope) and flags assumptions. It stops short of stating the concrete response shape or how 'assumed' defaults are surfaced, so it is strong but not exhaustive.

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%, so the schema already documents all eight optional parameters, including the 'omit when unknown' defaults and the paired length/width rule. The description adds only indirect hints (footprints, orientation) rather than parameter syntax or units beyond what the schema provides, 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 dual purpose with concrete verbs and resources: 'Check whether a pickleball court fits a space and show public court project costs.' It then enumerates what returns (rulebook footprints, one-court fit in either orientation, cost cards, unpriced scope), so 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?

Gives clear context for when it applies (fit checking a space against rulebook dimensions, and sourcing public project cost figures) and warns that the cost cards are 'not a price for this court.' It does not name explicit exclusions or contrast against sibling cost calculators, but the domain is narrow enough that routing is unambiguous.

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