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

Annotations already cover the safety profile (read-only, idempotent, non-destructive, closed-world), so the bar is lower. The description adds real context beyond them: it discloses the output contents (arithmetic target, additional limit needed, and the $0–$10M scenario ladder) and attaches an explicit disclaimer that the result is not a quote or a legal determination — a behavioral trait no annotation conveys.

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 sentences, front-loaded with the calculation inputs before the return values and the scope caveat. Every sentence earns its place; the enumerated scenario ladder is slightly verbose but informative about output shape.

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?

An output schema exists and the description still summarizes returns, annotations cover safety, and parameters are fully documented. The remaining gap is the absence of any routing guidance relative to umbrella_calculator and umbrella_underlying_limit_check in a crowded umbrella namespace.

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% with five well-documented parameters, so the schema already carries the semantics. The description restates the input categories and hints at their relationships (protected assets must be independently confirmed, income allowance optional, underlying limit is the lowest applicable), but adds nothing the schema doesn't already say more precisely.

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 pair: comparing how much umbrella coverage to consider from named inputs (net worth, protected assets, income allowance, underlying limit). The scope boundary ('planning, not a quote or a determination of legally exposed assets') further sharpens what the tool is. It does not, however, name or contrast with close siblings such as umbrella_calculator or umbrella_underlying_limit_check, so the agent must infer the split.

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 implies the tool is for planning-level comparison and explicitly excludes quoting and legal exposure determination, which helps an agent know what not to expect. But it never states conditions that select it over umbrella_calculator or umbrella_underlying_limit_check, leaving the sibling choice to inference.

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