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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds little beyond enumerating return fields, which the output schema already carries, so it clears the lowered bar but adds only marginal context.

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 sentences, front-loaded with the purpose, which is good structure. However, roughly half the text enumerates return fields already fully specified by the existing output schema, so that sentence does not earn its place.

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 read-only, fully-annotated calculator with 100% schema coverage and an output schema, the definition supplies what an agent needs to invoke it. The only real gap is the absence of guidance situating it among the many sibling finance/retirement calculators.

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% and every parameter (age, salary, contribution_pct, employer_match_pct, employer_match_limit) is documented in the schema with defaults and ranges. The description adds no parameter syntax or semantics, so the baseline 3 applies.

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 verb and resource ('Calculate US 401(k) contribution, employer match, and total retirement savings'), which is more precise than most siblings like calculate_retirement_pension. It does not explicitly distinguish itself from adjacent tools such as calculate_us_paycheck or calculate_retirement_savings_gap, so it stops short of a 5.

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?

There is no statement of when to use this tool versus alternatives; it only points at list_bundles for discovering related 'finance-us' calculators. The age-50+ catch-up condition is a schema-level detail, not usage guidance for tool selection.

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