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 covered. The description adds one genuinely useful behavioral fact – that a built-in current small-savings rate is used when ratePct is omitted – but says nothing about compounding conventions, which rate year is used, or how FD/RD tenure is defaulted when months is absent.

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 short sentences with no filler; the scheme list is front-loaded and the rate-default caveat follows immediately. Every clause carries information an agent needs.

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?

An output schema exists, so return-value explanation is rightly omitted. However, for a 5-parameter calculator with two required fields, the description leaves ambiguity about tenure selection (years vs months) and default tenure for FD/RD, which an agent must resolve before calling.

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 coverage is 60%, and the description usefully clarifies the ratePct parameter ('unless a rate is given') and that amount means yearly deposit for PPF/SSY versus principal for FD versus monthly for RD. The scheme enum and the interaction between years and months still rely on the schema, so 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 names the computed quantity (maturity value) and enumerates the four supported schemes (PPF, Sukanya Samriddhi, fixed, recurring deposits), so an agent can map it against siblings like calculate_gst or salary_in_hand. It stops short of an explicit verb phrase such as 'computes/returns', which keeps it from 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 explicit when-to-use or when-not-to-use statement, and no alternative tool is named. The clause about falling back to current small-savings rates implies the intended context (quick estimates in INR) but it is left to inference.

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