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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds real behavioral context beyond them: the thin-absorber assumption (results are not valid for thick targets) and the beta*gamma 0.05 truncation of the range, which tells the agent when results stop being trustworthy.

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 dense sentences, front-loaded with the model and result types, then the validity limit, then the inputs. Slightly telegraphic ('give momentum or kinetic energy and thickness') but no wasted text.

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?

With no output schema, the description should say what comes back; it says 'estimates and a CSDA range' but gives no units or output structure for the loss estimates. Physics validity and input modes are covered, so it is adequate but leaves a real gap for a 6-parameter scientific 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?

Schema coverage is 100%, so every parameter including the momentum/kinetic either-or is already documented. The description's 'give momentum or kinetic energy and thickness' merely restates the schema without adding units, ranges, or precedence rules, so baseline 3 applies.

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?

Names the specific physics models (Bethe, Landau, CSDA range) and the resource (heavy charged particle energy loss), so an agent knows exactly what computation happens. It does not, however, distinguish itself from the closely related sibling synchrotron_loss or photon_attenuation, which an agent would need to choose between.

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 phrase 'range is truncated at beta*gamma 0.05' implicitly states the validity domain (low-beta particles are out of scope), which is useful usage context. But there is no explicit when-to-use versus the sibling loss/attenuation tools, and no exclusions beyond the implicit truncation.

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