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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered by structured data. The description adds only the fact that returned keys feed calculate_materials; it says nothing about ordering, count, or shape of the returned list. Useful but thin context on top of annotations.

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?

Two short sentences with zero filler, and the resource identification is front-loaded ahead of the workflow hint. Every clause earns its place.

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?

For a zero-parameter, read-only listing tool with no output schema, the description covers what it returns (calculator identifiers) and how they are consumed downstream. Nothing critical is missing, though a hint about whether the list is stable/complete would close the remaining gap.

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?

The tool takes zero parameters, so per the rubric the baseline is 4. There is nothing for the description to explain, and it correctly doesn't invent parameter guidance.

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 names the resource (material calculators on furringline.com) and scopes it with concrete examples (ceilings, partition walls, insulation), so an agent knows exactly what comes back. It stops short of an explicit verb like 'lists all', relying on the title for that, but the scope is unambiguous.

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?

'Use a key with calculate_materials' tells the agent this tool is the entry point that produces input for the sibling calculate_materials, which is real routing guidance. It doesn't state an explicit when-not to call it or cover the other siblings (get_product, search_products), so it falls short of a 5.

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