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 goes further by disclosing the exact algorithm (pitch factor √(1+(rise/12)²), overhang added to both dimensions, waste multiplier), which tells the agent this is deterministic, side-effect-free math and exactly how inputs combine. It stops short of noting defaults are silently applied or how results are formatted.

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 sentences, front-loaded with the purpose, then the math. The formulas are dense but each one earns its place by defining an otherwise ambiguous conversion. Slightly formula-heavy for a description, but no filler or repetition of the title.

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 carries the return-value burden and largely does so by naming the computed outputs (area, squares, bundles) and units. It omits the exact response shape and the fact that all six parameters default when omitted, which slightly under-serves an agent preparing a call, but the core contract is present.

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 adds real meaning beyond the schema text: it shows overhang_in is applied to both length and width, pitch_rise feeds rise/12, and waste_pct is a multiplicative allowance. It does not, however, show how bundles_per_square is used to reach the bundle count, leaving that one parameter's effect implicit.

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 computation with named outputs: roof area from footprint and pitch, converted to roofing squares (100 sq ft) and shingle bundles. An agent can tell this is a roofing-material takeoff calculator without opening the schema, and it is distinguishable from generic area tools like calc_sod or calc_paint by the pitch-factor and bundle output.

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 by the formula and units (squares, bundles), which signals the roofing-takeoff scenario, but the description never states when to use this versus siblings like calc_asphalt or calc_rafter_length, nor any prerequisites (e.g., that it works from a rectangular footprint only). The guidance is inferable, not explicit.

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