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

Annotations already cover read-only, idempotent, non-destructive behavior, so the safety profile is settled. The description adds the genuinely useful constraint that exactly two of the three inputs must be supplied and the third is returned, which the schema cannot express since all three parameters are optional. It does not describe error behavior when too few inputs are given.

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?

Three tight sentences with the formula and solve-for-any behavior front-loaded; the discovery pointer to list_bundles is short and earns its place. No filler or repetition.

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 simple three-input read-only calculator with an output schema present, the description covers what the tool does, which inputs are needed, and what comes back. Nothing essential 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 the baseline is 3. The description maps the symbols to the fields (V volts, I amps, R ohms) and states the two-of-three relationship, which is modest added meaning over the schema's terse "Amps"/"Volts"/"Ohms" labels but no syntax or edge-case detail.

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 (compute Ohm's law, V=I·R) and the exact operation (solve for any of V, I, R given the other two). The agent can tell this apart from adjacent electrical siblings such as calculate_electrical_power without opening the schema.

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 for electronics" gives an implied context, and it points to list_bundles for related 'science' calculators, but it never states when to pick this over calculate_electrical_power or calculate_voltage_adapter, nor any exclusion. Usage is implied rather than explicit.

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