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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description goes further by disclosing the exact deterministic formulas used (pitch factor, ridge rise, angle via atan), which lets an agent predict output precisely. It stops short of stating output units, which would complete the behavioral picture.

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-loaded with the computed outputs, followed by a compact formula block that is terse and information-dense. The three formula sentences each carry distinct value, though the notation is dense enough that plain-prose framing would aid readability slightly.

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 correctly enumerates the three return values (rafter length, ridge rise, roof angle), which is exactly what the agent needs. The remaining gap is output units (rafter/ridge presumably feet, angle degrees) and the fact that all three parameters are optional with defaults.

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 run_ft, pitch_rise and overhang_in with units and defaults, establishing a baseline of 3. The description's formula adds the relationship between overhang and run (added together before multiplying by pitch factor), but no meaning beyond that.

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 precise verb+resource: computes common rafter length, ridge rise and roof angle from run and pitch, plus optional overhang. This clearly separates it from siblings like calc_roofing (material estimation) or calc_stair_stringer (different geometry), so an agent can select it 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?

The description explains the required inputs but gives no when-to-use guidance, no prerequisites, and no mention of when to choose calc_roofing instead. Usage is only inferable from the formula, which the calibration treats as insufficient guidance.

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