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

No annotations are provided, so the description carries the full burden. It usefully discloses that out-of-range values are snapped rather than rejected, that results are compared against a benchmark, and that backtests are real/expensive — but it omits how costly, whether there are rate limits, or any auth/permission prerequisites.

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?

Four short sentences, front-loaded with the core action and then the return content, the snapping behavior, and a cost warning. Every sentence roughly earns its place, with only mild rhetorical padding in the last clause.

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 no output schema, the description steps in to say results are "figures against its benchmark," and it covers the enum window behavior, default handling, and value snapping. For a 3-parameter tool with full schema coverage, this is nearly complete; only cost/limit specifics are missing.

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 id, range, and params semantics are already documented (including the enum window values and the default-for-omitted-keys behavior). The description's range note ("only these are kept warm; anything else is refused") and the snapping rule add context but little that the schema doesn't already carry.

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: run a published strategy over real market history with chosen parameters. "Published strategy" implicitly separates it from the sibling backtest_code (which would run user-supplied code), though that sibling is not named explicitly.

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?

No explicit when-to-use or alternative routing; the closing "This is a real backtest, so make each one count" only implies the operation is costly and should not be spammed. An agent must infer that backtest_code is the alternative for custom logic.

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