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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is handled. The description adds meaningful behavioral context: the tool is pure arithmetic on given numbers, produces no advisory output, and IU/mL depends on a peptide's documented factor. Minor gaps remain (e.g., handling of invalid inputs like zero volume) but the key behavior is disclosed.

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 tightly written sentences. The formula and output units are front-loaded, followed by a concise scope boundary. Every sentence earns its place with no redundancy.

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 that an output schema exists (so return values need not be described), annotations cover safety, and the input schema has full description coverage, the description provides exactly the missing context: the calculation performed, output units, and the fact that it is purely arithmetic without preparation advice. Nothing essential is missing 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 description coverage is 100%, so the baseline would be 3, but the description adds value by stating the exact formula (amount ÷ volume), the resulting units, and the role of the optional peptide parameter for IU/mL. This meaningfully supplements the schema's field-level documentation.

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 calculation (concentration = amount ÷ volume) and the output units it produces (mg/mL, mcg/mL, IU/mL). It clearly distinguishes this pure arithmetic tool from advisory or preparation tools, but it does not name or contrast with any sibling tool (e.g., convert_units or blend_concentrations).

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?

Usage is implied by the calculation context, and the description adds a useful negative constraint ('it does not suggest amounts, volumes or how to prepare anything'). However, it never explicitly says when to choose this tool versus alternatives like convert_units or blend_concentrations, so the agent must infer routing.

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