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

Goes beyond the readOnly/idempotent annotations by disclosing the selection mechanism (deterministic, no LLM judgement, reproducible) and that output carries the margins that drove ranking. It does not cover what 'options' or 'include_envelope' change in behavior, but the core behavioral character of the selector is clear.

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?

The operative clause is front-loaded and tight, but 'Kelvin's deterministic selector' and 'Same authority Kirchhoff and Heaviside select through' are persona branding that consumes roughly half the text without helping an agent invoke the tool.

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?

A five-parameter tool with nested objects, 0% schema coverage, and no output schema needs the description to explain the shape of the requirements block and the effect of options/envelope. The description leaves both the input shape and the return structure largely unspecified.

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 0% across five parameters including two nested objects, and the description only gestures at 'requirements' as a designRequirements block. The 'family', 'options', 'max_results', and 'include_envelope' parameters are left entirely unexplained, so the coverage gap is not compensated.

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 a specific verb and resource: 'rank real parts against a designRequirements block' and states what comes back ('candidates with the margins that ranked them'). It never names a sibling (search_parts, cross_reference) to draw the boundary, so differentiation has to be inferred from the word 'rank'.

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?

Implies usage by requiring a 'designRequirements block', which suggests this is the tool for constraint-driven selection rather than free-text lookup. It gives no explicit when-not conditions and no alternative named, so an agent choosing between this and search_parts or cross_reference gets no routing help.

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