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

With no annotations at all, the description carries the full behavioral burden. It never says whether the result is a single scalar or a time series aligned to the inputs, how the first input point is handled, or what units the output carries — all of which matter for a derived numerical indicator.

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 definition of the indicator before the input requirement. The 'Obv:' prefix duplicates the tool name and is mildly redundant, but there is otherwise no wasted text.

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?

There are no annotations and no output schema, so the description is the only source of behavioral detail. It explains what OBV is but not what the tool returns or how to interpret it, which is inadequate for a numerical computation whose output shape is entirely undocumented.

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 listed at 100%, but the schema descriptions are generic placeholders ('Close to process', 'Values to process', 'Volume to process'). The description adds that 'close' and 'volume' are arrays, which the schema (typed as strings) does not convey, but it silently ignores the third parameter 'values', leaving it unexplained.

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 states a specific verb ('Calculate') and resource ('On-Balance Volume (OBV)'), and further classifies it as a volume-based momentum indicator, which is enough to distinguish it from generic siblings like x402-volume. It stops short of naming which sibling to prefer (e.g. vs x402-vwap-calc or x402-rsi), so no explicit sibling differentiation.

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?

There is no when-to-use versus when-not-to-use guidance and no named alternatives. 'Provide close price and volume arrays' is an input instruction, not a usage guideline, and it does not say in what analytic context OBV is preferable to other indicators.

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