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 publishing the exact formulas used, letting an agent predict and sanity-check the numeric output rather than treating it as a black box.

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 sentences: the purpose comes first and the formula second, with no filler. The formula sentence is dense but each symbol maps directly to a named parameter, so nothing is wasted.

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 read-only calculator with fully documented optional parameters and no output schema, the description tells the agent what the two possible returns are (cubic yards or bag count) and how they are derived. Minor gap: it says '80 lb bags' while bag_yield_cf is configurable, so the default assumption is not reconciled.

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 units and defaults are already documented and the baseline is 3. The formulas add real meaning by showing each parameter's role: thickness enters as /12, waste_pct as a (1 + waste%) multiplier, and bag_yield_cf as the divisor converting cubic feet to bags.

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 ('Estimate ready-mix cubic yards or the number of 80 lb bags') and scopes it to a rectangular slab, patio or driveway. This clearly separates it from sibling calculators dealing with footings, columns, or concrete block.

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 phrase 'rectangular slab, patio or driveway' implies when the tool applies, but no alternative is named even though siblings like calc_concrete_footing, calc_concrete_column, and calc_concrete_block are the obvious competing choices. Usage is inferable but not routed.

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