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

The annotations already establish the safety profile (readOnly, idempotent, non-destructive, closed-world), so the burden is light. The description earns credit for disclosing a behavioral trait the annotations cannot: that the tool returns an extra derived value (photon energy E=hf) beyond the raw wavelength/frequency solve.

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 short sentences, front-loaded with the governing equation, then the input rule, then the extra output, then a cross-reference. Every sentence carries information and nothing is padded.

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 pure two-input calculator with an output schema and full annotation coverage, this is nearly complete: inputs, governing relation, supplementary output, and a pointer to related bundles. It only omits edge-case behavior (e.g. what happens if both or neither value is supplied).

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 schema already defines both numeric parameters and their units, making 3 the baseline. The description adds genuine meaning the schema lacks: that the two inputs are alternatives ('provide wavelength or frequency') rather than both required, since the schema marks neither as required and gives no either-or guidance.

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 gives a specific verb and resource ('Solve c=λ·f for EM waves') plus the supplementary output (photon energy E=hf), so an agent knows exactly what computation happens. It does not explicitly distinguish itself from near-neighbours such as calculate_wave_properties or calculate_frequency_note, so it stops short of a 5.

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?

'Provide wavelength or frequency' tells the agent which inputs to supply, which is useful invocation context, but there is no statement of when to prefer this tool over the other wave/frequency calculators in the sibling list, nor any when-not condition. Usage is implied rather than spelled out.

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