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

Annotations already declare a safe, read-only, idempotent, closed-world computation, so the bar is lower. The description does add real behavioral value beyond them: it discloses that the tool performs two runs (given order and reverse) and compares ending balances, which is the core logic. However, it says nothing about what is returned (balances only, per-year series, chart data) despite having no output schema, so transparency is incomplete.

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, front-loaded with the tool's identity and then the mechanics; nothing is padded. The phrase 'with an interactive chart' is mildly wasteful since it describes presentation rather than capability, but it is not misleading.

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 three-parameter, annotation-covered, no-output-schema tool, the description covers the computation well but leaves the response shape entirely unspecified — an agent cannot tell whether it gets two final balances, a year-by-year series, or chart data. With no output schema, that gap matters.

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 documents start_balance, annual_withdrawal, and the per-year returns_pct array with bounds. The description adds only mild context: that the withdrawal is fixed across years and that order is preserved. That is enough for the baseline 3 but nothing more.

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 a specific computation (sequence-of-returns) and states precisely what it does: runs a list of yearly returns with a fixed withdrawal forward and in reverse and compares ending balances. That is a distinctive verb+resource combination an agent can match to a user question. It does not explicitly differentiate itself from siblings like compound_interest or drawdown_recovery, keeping it at 4.

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?

Usage is only implied: an agent can infer it should be used when the ordering of returns matters and a withdrawal is involved. There is no explicit when-to-use, when-not-to-use, or named alternative such as compound_interest for order-independent growth. Adequate but with a clear guidance gap.

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