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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real behavioral value by disclosing the exact formula, the editable density assumption, and the waste/bag-rounding behavior (⌈pounds ÷ bag size⌉), which tells the agent precisely how inputs map to outputs.

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 in the first sentence, then supplies the formula in a compact notation. The formula is dense but every clause maps to a parameter or output, so it largely earns its space.

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 names both return units (pounds and bags) and explains the rounding rule for bags. All eight optional parameters with defaults are semantically covered, so an agent has everything needed to call and interpret the tool.

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, but the formula goes beyond the schema by showing how each input participates: L, W, J, depth, area, density, and waste all appear in the joint-share and volume equations. Density is explicitly flagged as product-dependent (~100 sanded, ~85 unsanded).

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 verb and resource — computing grout quantity (pounds and bags) from tile size, joint width, joint depth, and area. This is clearly separable from the sibling calc_flooring_tile, which covers tile count rather than grout consumption.

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?

The scope (tile job grout amount) implies when to use it, but there is no explicit routing advice versus calc_flooring_tile or other tiling siblings, and no statement of assumptions or prerequisites. Usage is inferable but not guided.

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