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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful domain context that the annotations cannot convey: NRE and FCNR(B) interest is tax-free while non-resident, NRO is taxed, and treaty rates require a tax residency certificate. It still says nothing about what the response contains (maturity value, interest, TDS breakdown) or how quarterly payout changes results.

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?

It is a single compact sentence with no filler, but it is front-loaded with an illustrative rupee figure rather than the tool's function, so the agent reads a number before learning what the tool computes. The trailing URL is low-value for tool selection.

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 an 8-parameter tool with no output schema, the description should say what comes back — maturity amount, interest earned, TDS deducted, post-tax total — and it does not. Interactions between the payout and compounding enums, and the meaning of the treaty codes, are left entirely to the schema, so an agent cannot predict the response shape.

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 baseline is 3. The worked example goes beyond the schema by binding concrete values to parameters (₹10 lakh principal, 6.5% rate, 3 years, NRE vs NRO depositor, UAE treaty) and showing how depositor plus treaty jointly change the result, which is meaningful semantic guidance the enum list alone does not provide.

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 phrase 'FD calculator after TDS' identifies the resource (fixed deposit) and the distinguishing tax dimension, so an agent can tell it is a maturity/proceeds calculator rather than a loan tool. However, it never states the purpose in a clean sentence and offers no differentiation from close siblings such as cd_calculator, compound_interest_calculator, or simple_interest_calculator. The opening is an example result rather than a definition of what the tool does.

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 guidance, and no sibling is named as an alternative. The NRE/NRO example implies the tool applies to non-resident Indian fixed deposits, but the agent must infer that from a worked example rather than a stated condition.

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