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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds that it returns area, perimeter and a triangle type, plus the formula used, which is useful context beyond the annotations; it omits any note about invalid inputs (triangle inequality violations).

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?

Four short sentences, front-loaded with the core action and method; no filler. The trailing cross-reference to list_bundles and the minor typo 'isoceles' are the only blemishes.

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?

An output schema exists, so return values need not be enumerated, yet the description still sketches them. For a three-parameter, closed-world, idempotent read tool, nothing needed to invoke it correctly is missing.

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 a baseline of 3 applies. The description's 'Inputs: sides a, b, c' merely restates the schema's own 'Side a/b/c' descriptions and adds no units, ordering, or validity constraints.

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 (compute) and resource (triangle area) and names the exact method (Heron's formula from three side lengths). This clearly separates it from the many geometry siblings such as calculate_pythagoras, calculate_trigonometry, and calculate_area.

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 when angles aren't known' gives a concrete selection condition against the angle-based alternatives. It stops short of naming the sibling to prefer instead (e.g. a trig-based area tool), so it is clear context but not full when/when-not routing.

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