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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered and the bar is lower. The description adds nothing beyond the operation list: it does not say what happens on dimension mismatch, whether magnitude/unit ignore vector_b, or how invalid operations are reported, even though an output schema exists to cover return shape.

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?

A single compact fragment with no filler, and the operation list is front-loaded as the core of the sentence. It is appropriately sized for a simple calculator tool, though the terseness contributes to the missing conditional-parameter detail.

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?

The tool is simple and has an output schema, so return values need no explanation. Still, the most decision-relevant facts for this dispatcher-style tool — conditional requirements on vector_b and dimension constraints per operation — are absent from both the description and the schema descriptions.

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 vector_a, vector_b, and operation are all documented in the schema, giving a baseline of 3. The description restates the operation values (dot, cross, magnitude, unit, add, subtract) but adds no new semantics, and it does not clarify that vector_b is conditionally required for dot/cross/add/subtract.

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 (vector operations) and enumerates six specific operations, so an agent knows exactly what capability is behind the tool. However, it makes no attempt to distinguish itself from the dedicated siblings calculator_dot, calculator_cross, calculator_magnitude, and calculator_unit_vector, which cover a subset of the same ground.

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?

There is no guidance on when to pick this multi-operation tool versus the dedicated single-operation siblings that appear in the sibling list. It also doesn't state the key preconditions that would change an agent's behavior, such as cross product requiring 3-component vectors or add/subtract requiring equal dimensions.

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