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

With no annotations, the description must disclose behavior, but it only states the calculation outputs without revealing formulas, rounding behavior, assumptions (e.g., center-to-center spacing, waste factor), or how cost is computed. The phrase 'exact posts, rails, and pickets' suggests precision, but no underlying logic is disclosed.

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?

The description is a single, focused sentence that front-loads the tool's name and core function. It efficiently conveys key inputs and outputs with no redundant or extraneous text.

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?

Given the tool has 8 parameters, no output schema, and no annotations, the description is too sparse. It fails to explain all required inputs, the output format, cost calculation specifics, or any constraints (e.g., units, rounding). The description covers the broad purpose but leaves substantial gaps for correct invocation and interpretation.

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 0%, and the description only maps three of eight parameters: 'run length' (fenceLength), 'post spacing' (postSpacing), 'picket width' (picketWidthIn). It omits gapIn, railsPerSection, and the price parameters entirely, leaving those meanings vague despite their presence in the schema. Partial compensation is insufficient for 8 parameters.

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 clearly states the tool's purpose: 'Calculate fence materials fast' with a specific resource (fence posts, rails, pickets) and mentions inputs (run length, post spacing, picket width) and outputs (exact posts, rails, pickets, optional cost). This distinguishes it from sibling calculators like deck_boards_calculator or concrete_calculator.

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?

Usage is implied: users with fence measurements would use this calculator. However, there is no explicit 'when to use this vs alternatives' or exclusion criteria. The description gives a functional hint but lacks direct guidance compared to more explicit alternatives.

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