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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds meaningful context beyond annotations by defining mach at 340.29 m/s and citing the source URL, which clarifies the exact conversion basis an agent needs.

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 concise sentences convey the action, supported units, conversion constant, and source. There is no fluff, and the core purpose is front-loaded in the first sentence.

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?

Given the simple schema, full output schema, and safety annotations, the description is complete. It covers all units, gives the key Mach reference, and includes a source link, leaving no critical gap for correct invocation.

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 baseline is 3; the description adds value by expanding the enum abbreviations into full unit names and specifying the Mach constant. This gives the agent practical meaning beyond the raw schema enum values.

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 states a specific action ('Convert a speed') and resource (speed units), and lists all supported units with abbreviations. This clearly distinguishes it from sibling unit converters (length, weight, volume) by naming the speed domain explicitly.

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 speed-specific wording makes the intended use clear, but it does not explicitly state when to prefer this tool over sibling converters or give exclusions. Usage is implied rather than directly routed, so it does not reach the level of explicit guidance.

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