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

Annotations already declare this a safe, idempotent, non-destructive, offline read. The description adds that the result includes FV and total interest, but that duplicates the output schema, and it discloses nothing about rounding, decimal conventions, or how negative/zero edge cases behave. Adequate but thin given the low bar set by full annotation coverage.

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?

Four short sentences, front-loaded with the core computation and ending with a useful bundle pointer. The input enumeration partly restates the schema and introduces the erroneous compounding-frequency item, costing a little efficiency.

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 three-parameter calculator with an output schema and full annotations, the description covers purpose, a use case, and return values. The unsupported compounding-frequency claim is the one material gap that could cause an incorrect invocation.

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 the schema already defines present_value, rate, and years. However, the description lists 'compounding frequency' as an input while the schema has only three properties and additionalProperties:false, so the extra named input is phantom and likely to mislead an agent into searching for a parameter that does not exist.

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 ('Compute the future value (FV) of a present sum at a given interest rate'), which is distinct from the inverse calculate_present_value and from calculate_compound_interest. It does not explicitly name the sibling it differs from, 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?

'Use for savings projections' gives one positive context but no when-not conditions and no routing among the many finance siblings (calculate_present_value, calculate_compound_interest, calculate_annuity_payment). The cross-reference to list_bundles is a generic pointer, not an alternative-selection rule.

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