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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description adds that the calculation includes current savings and interest and returns a monthly deposit, but does not disclose compounding frequency, rounding, or other calculation assumptions.

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 and front-loaded with the use case and computed output. The trailing web page URL is non-essential for invocation but does not obscure the core instruction.

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 simple read-only calculator with full schema coverage and clear annotations, the description identifies the main output (monthly deposit) and relevant inputs. Although there is no output schema, the tool's purpose is clear; minor omissions like compounding and currency handling are covered by the input schema.

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 all five parameters have documented names and constraints. The description only restates goal, deadline, current savings, and interest through an example, adding no semantics beyond what the schema already provides.

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: 'shows the monthly deposit' for a 'savings goal calculator' using target, deadline, current savings, and interest. It does not explicitly distinguish itself from similar siblings such as compound_interest_calculator or retirement_calculator, so it falls 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?

Offers a representative scenario ('Need $50,000 in 5 years?') that implies when the tool is useful, but provides no explicit when-not-to-use guidance or named alternatives. In a large sibling set of financial calculators, this leaves routing somewhat to inference.

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