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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, so the safety profile is covered. The description adds value by stating it does not change page or account state, does not access BetterOff customer data, and does not provide personalized financial advice—context beyond the annotations that tells the agent what side effects and data access are absent. This is a meaningful addition for a public calculator.

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 with no filler. The first sentence states the core purpose and calculations, and the second clearly delimits what it does not do. The key behavioral constraints are front-loaded and easy to scan, making it efficient for an agent to parse.

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 (6 params, no required fields), an output schema, and comprehensive annotations, the description is sufficiently complete. It covers purpose, read-only nature, and data-access limitations. The output format is handled by the output schema, so no further return-value details are needed. Minor omissions like edge-case behavior are not critical for a calculator of this type.

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%, so each parameter already has a clear description. The description's phrase 'from monthly expenses and coverage months' only highlights two of the six parameters, but the schema handles the rest. Since the schema does the heavy lifting, a baseline 3 is appropriate; the description adds no parameter-level nuances beyond the schema.

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?

Description clearly states a specific verb and resource: 'Read-only educational calculator' for calculating emergency fund target, tracking progress, and estimating time-to-goal. It distinguishes itself from siblings by its educational, read-only nature and its focus on emergency funds, setting it apart from calculators like calc_savings_goal or calc_fire. The phrase 'without... providing personalized financial advice' further clarifies its scope.

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 provides clear context: it is a read-only educational tool that works from caller-supplied public inputs and does not access customer data or give personalized advice. This implicitly tells the agent when to use it (when a simple, non-personalized estimate is needed) and when not to (when personalized advice is required). It does not name specific alternatives, but the context is strong enough for tool selection.). It lacks explicit 'use X instead' guidance, but the boundaries are well-defined.

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