engineering.parallel_reliability

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

Annotations already cover read-only/idempotent/closed-world, so the bar is lower; the description adds meaningful behavioral context beyond them: the independence assumption, the no-rounding/50-significant-digit precision guarantee, and the string-typed decimal input convention.

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?

Front-loads the formula, then constraints, then exclusions, then precision — a logical order with little waste. Four dense sentences is appropriate, though the input-format note could be tightened slightly.

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?

For a single-parameter calculation tool with an output schema (so return values need no explanation) and full annotations, nothing an agent needs to call it correctly is missing: input format, domain constraints, structural assumptions, exclusions, and numeric precision are all covered.

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 0%, so the description must carry the parameter meaning — and it does: a list of numeric strings, at least one element, each in [0, 1], written as decimals such as 0.99. This resolves the non-obvious string-typed array quirk that the schema leaves unexplained.

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 and resource plus the exact formula (R_sys = 1 − Π(1 − R_i)), which uniquely identifies this as the parallel/redundant reliability tool among siblings like engineering.series_reliability and engineering.exponential_reliability. An agent can distinguish it without opening the schema.

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?

Explicitly defines the applicability condition (system works if any one component works, components independent) and an exclusion (k-of-n structures are not supported). It does not name the sibling tool to use instead for series or k-of-n cases, so the alternative routing is left implicit.

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