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

Annotations already mark the tool as read-only, idempotent, and non-destructive. The description adds meaningful behavioral detail beyond those annotations, notably that it uses the IRS unisex mortality table, evaluates how long the lump sum lasts, computes the required return, and produces a verdict. It does not describe the exact output format, but the key assumptions are disclosed.

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 a single, well-structured sentence that front-loads the core comparison and then lists the computed metrics. Each clause adds a distinct output with no filler, though the sentence is dense and somewhat long.

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 complex financial planning tool with no output schema, the description enumerates the major outputs and key assumptions, which is sufficient for an agent to understand what the tool will compute. It does not specify return types or units, but the schema covers parameter details and the selection purpose is fully clear.

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 each parameter already has a clear description and defaults. The tool description does not repeat those details, but it does connect the output concepts to parameters like planning age, expected return, and monthly pension. This meets the baseline for full schema coverage.

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 opens with a concrete verb, 'Compares', names the exact objects (the pension's lump-sum offer vs. its monthly annuity), and enumerates the specific outputs: payout rate, exhaustion age, required return, survival odds, and a verdict. This makes the tool's purpose unmistakable and distinguishes it from siblings such as how_long_will_money_last even without naming them.

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?

The description clearly conveys the intended scenario: evaluating whether to take a pension lump sum versus an annuity, with planning-age and return assumptions. It does not explicitly state when not to use this tool or name alternative tools, so it lacks exclusion guidance, but the use context is unambiguous.

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