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

Annotations already cover safety (readOnly, idempotent, non-destructive), yet the description adds real behavioural context: the SpekPy 2.5.4 engine, 12-degree anode, 2.5 mm Al inherent filtration baked into results, interpolation between stored kVp, XCOM filters and NIST SRD 126 mu_en/rho, and the scatter-free inverse-square geometry. It stops short of stating accuracy limits or failure modes, so not quite a 5.

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 sentences, front-loaded with the deliverable quantities so an agent sees the outputs first. The second sentence is dense with implementation detail (SpekPy version, interpolation scheme, SRD 126) that is partly engineering trivia, keeping it from a 5.

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?

No output schema exists, so the description carries the burden of naming return values, which it does completely (spectrum, mean energy, HVLs, air kerma, removed kerma fraction). It does not say how those results are structured or packaged, a minor residual gap for a pure computation tool.

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?

With 75% schema coverage the schema already documents kVp range, mAs, distance and filter thickness. The description reinforces 'added filters' and 'inverse-square distance' but adds little syntax or format meaning beyond the schema, and never ties mAs to the fluence/air-kerma scaling explicitly.

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 ('Calculate') plus an enumerated set of concrete resources: tungsten tube spectrum, fluence-weighted mean energy, Al/Cu HVLs, air kerma and filter-removed kerma fraction. This clearly separates it from generic siblings like photon_attenuation or gamma_dose_rate, which do not generate tube spectra.

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 is only implied by the output list and the physics caveats ('Narrow beam without scatter'), so an agent can infer this is for diagnostic-kVp spectral modelling but gets no explicit when-to-use, when-not, or named alternative among siblings such as photon_attenuation.

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