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

With no annotations provided, the description carries the full burden of explaining behavior. It discloses the key outputs (Kv, Cv, choked-flow check, cavitation index with assessment) and specifies that pressures are in bar absolute, which is critical for correct usage. It does not disclose error handling or limitations, but for a calculation tool this is adequate.

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 concise sentences deliver the purpose, key outputs, and unit convention with no filler. Front-loaded with the main task, then details, making it easy to scan.

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 the tool's moderate complexity (7 parameters, no output schema), the description covers the essential return values and key unit constraints. It does not describe the exact format of the assessment or edge cases, but for a calculation tool with self-explanatory parameters, this is sufficient.

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?

The schema already provides descriptions for all 7 parameters (100% coverage), so the baseline is 3. The description adds value by specifying that pressures are in bar absolute, removing ambiguity for the three pressure parameters. It also associates 'FF' and 'dP limit' with the choked-flow check, giving context to how the parameters are used.

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 uses the specific verb 'Size' with a clear resource ('control valve for liquid service') and explicitly references the applicable standards (IEC 60534-2-1 / ISA 75.01). This immediately distinguishes it from the sibling tool control_valve_size_gas.

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 description clearly states the tool is for liquid service, which implies it should be used over the gas sibling. It does not explicitly name the alternative or provide when-not-to-use conditions, but the liquid-service qualifier is sufficient context for most selection decisions.

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