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

Annotations already declare the safe read-only, idempotent, closed-world profile, and the description adds real value on top: it generates a PNG artifact, returns results/conditions/assumptions/editable link/share page, and explicitly disclaims account access and order execution. It does not disclose rate limits or whether repeated calls accumulate artifacts, which is a minor gap.

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 compact sentences, front-loaded with the input model and then the outputs. Every clause carries information; it is dense but not padded.

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?

With a full output schema and rich annotations already present, the description only needs to add scope and side-effect context, which it does (PNG creation, no account/order access). Nothing critical is missing for correct 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 documents every parameter with ranges, defaults, and units; the description only echoes the unit conventions (USD, percent, whole years). Baseline 3 is warranted since the description contributes little beyond the schema.

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 ('Compound interest in USD') and enumerates the input dimensions (initial dollars, monthly dollars, annual return/fees/inflation, whole years) plus the artifacts it creates. It never names or contrasts the close sibling dca_backtest, so sibling differentiation is left to inference.

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?

Lists what the tool consumes and produces but gives no when-to-use guidance or routing against siblings like dca_backtest, drawdown_recovery, or historical_return. The only scoping statement ('No account access or order execution') is a safety boundary, not a usage condition.

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