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

Beyond the readOnlyHint annotation, the description discloses two important behaviors: the inclusion of %B and bandwidth columns, and the warm-up of the moving-average window on price history before startDate, which ensures values do not depend on the requested range's left edge. This adds significant context about data computation and edge-case handling that annotations alone do not provide.

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 concise—three sentences that front-load the tool's purpose, then explain the calculation, interpretation, included columns, and a nontrivial edge-case behavior. Every sentence contributes meaningful information without waste or redundancy.

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?

Despite the absence of an output schema, the description adequately explains what the tool returns (BB bands, %B, bandwidth) and how the indicator behaves relative to the requested date range. It also covers the key formula components and the smoothing effect of the warm-up, providing enough detail for an agent to understand the tool's behavior without missing critical information.

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 baseline is 3. The description adds value by explaining how parameters affect the output: 'moving average of close' corresponds to period, 'standard deviations above and below' corresponds to stdDev, and the warm-up behavior clarifies startDate semantics. This is more than just restating the schema, though it does not delve into every parameter detail, hence a 4.

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 'Bollinger Bands for a stock', clearly identifying the tool's purpose. It provides specific details about the calculation (middle band, upper/lower bands, standard deviations), distinguishes it from sibling indicators like GetAverageTrueRange or GetStochasticOscillator, and mentions included columns (%B, bandwidth), making the tool's scope unmistakable.

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 context is provided through interpretive guidance: 'Bands widen when volatility rises and contract when it falls; price touching the upper/lower band is a common overbought/oversold cue.' This helps an agent decide when to use Bollinger Bands. However, it does not explicitly name alternatives or state when not to use this tool, so it falls short of a 5.

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