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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false. The description adds meaningful context beyond that: it explicitly says the tool returns a result from caller-supplied public inputs without changing page or account state, without accessing BetterOff customer data, and without giving personalized financial advice. These are behavioral guarantees not present in the annotations, so this is a strong transparency score.

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?

The description is two sentences, starts with the most essential fact ('Read-only educational calculator'), and packs the calculation scope and safety guarantees into a tight, front-loaded format. No filler or redundant phrases.

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 that an output schema exists (so return format is documented), the description covers the core behavior, safety profile, and generic inputs. The only gap is that it doesn't explain the 'mode' parameter (time_to_goal vs required_monthly) or how the calculator handles combinations of inputs, but for a straightforward educational calculator this is acceptable. Overall it leaves little critical information missing.

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 86%, so the input schema already documents all parameters well. The description maps inputs to high-level categories ('target, current balance, return, and deadline') but does not add much detail beyond the schema. It earns the baseline 3 for not contradicting or duplicating the schema, but it doesn't meaningfully expand parameter meaning.

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 ('Calculates') and identifies the exact outputs: savings-goal timeline, required monthly savings, and weekly equivalent. It clearly distinguishes this tool from sibling calculators by concentrating on savings-goal planning with a weekly-equivalent twist, so an agent can select it without guessing.

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?

Although the main use case is obvious ('calculates a savings-goal timeline'), the description provides no explicit guidance on when to use this tool versus any sibling (e.g., calc_compound_interest, calc_dca, calc_retirement). No when-not or alternative-routing information is included, leaving the agent to infer context from the name alone.

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