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

Annotations already declare the safe, read-only, idempotent profile, and the description adds real context beyond them: the computation uses the same function as the linked calculator page ('not estimated'), and it discloses the result shape (inputs, results with units, formula, page link) plus an educational disclaimer. It doesn't cover failure modes or bounds, keeping it short of a 5.

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?

Five short sentences, front-loaded with the definition so the agent grasps the operation before the input requirements. Slightly dense with the provenance and return-format clauses, but every sentence carries information an agent needs.

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?

No output schema exists, yet the description covers the return payload (inputs, each result with its unit, the formula, the page link), the input fallback rule, and provenance. Nothing needed to invoke the tool correctly is 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 coverage is 100%, so the baseline is 3, but the description adds the semantic relationship between parameters — entry combined with multiple×ATR, and the long/short sign flip — that the per-field schema text does not express. It also reinforces that ranges is an alternative to atr rather than a supplement.

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 ('A volatility (ATR) stop') and spells out the exact formula — entry minus/plus a multiple of ATR — which cleanly separates it from sibling calculators like calculate_position_size or calculate_risk_reward. An agent can tell instantly what this tool computes.

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?

It gives an input-selection rule ('Give atr, or at least five recent daily ranges') but never states when to reach for this tool versus the sibling risk calculators (position_size, risk_reward) or what regime it fits. Usage is implied by the tool's purpose rather than explicitly routed.

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