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

Annotations already declare a safe, idempotent, closed-world read-only calculation, so the bar is lower. The description adds real context beyond them: it is a pure arithmetic step with no side effects, the method source is MGD 005, and nearObject entries are informational ('listed here for the record') rather than affecting the shade factor computation.

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 core purpose is front-loaded and clear, but the passage runs several paragraphs and includes assessor methodology and a trailing MCS-methods/certified-installer disclaimer that does not help an agent invoke the tool. Useful content is diluted by educational and legal padding.

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 an output schema present, return values need not be explained, and annotations cover the safety profile. For a two-parameter, domain-specific calculator the description supplies enough method and boundary context to call it correctly, with only minor gaps around how nearObjects influence the result.

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 schema already documents both parameters thoroughly, including the segment/1%-irradiance relationship. The description largely restates that domain fact rather than adding new parameter-level detail; the '1 minus the loss' framing ties to the result but not to specific arguments. Baseline 3 is appropriate.

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 first sentence states a precise verb and resource: converting a completed MCS sunpath shading assessment into a shade factor via the MGD 005 procedure. It explicitly clarifies the boundary ('This tool does not perform the assessment. It does the arithmetic on an assessment somebody made'), which cleanly separates it from the assessment and the other solar_pv calculators (output, self-consumption, size).

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 context is clear: it applies only once an assessment has already been completed, and near-shading objects are assessed separately 'from each affected part of the array, not from its middle.' No sibling tool is named as an explicit alternative, so it stops short of full routing guidance, but the preconditions are well conveyed.

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