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

No annotations are supplied, so the description carries the full behavioral burden, and it discloses almost nothing beyond the computation. It does not say what the return value is (single MACD line vs MACD/signal/histogram set), whether periods have defaults when omitted, or output format. For a numeric-indicator tool with zero annotation coverage this is a significant 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 efficient sentences, front-loaded with the verb and resource before the inputs, with no filler. It could be slightly tighter but wastes nothing.

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 annotations, no output schema, and no default/return information, the definition is incomplete for a 4-parameter indicator tool. An agent still cannot know what it gets back, what happens when fast/slow/signal are omitted, or how many values are needed to produce a result.

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 baseline is 3. The description does add real meaning over the schema by naming the parameters semantically: it clarifies 'fast/slow/signal periods' and identifies 'values array' as the source series, whereas the schema's own descriptions are near-useless boilerplate ('Fast to process'). This marginally exceeds baseline but does not supply units, defaults, or the fact that all parameters are strings despite representing numbers.

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 ('Calculate') and resource ('MACD (Moving Average Convergence Divergence) indicator'), expanding the acronym so the agent knows exactly what it computes. It does not explicitly distinguish itself from adjacent siblings like x402-ema, x402-moving-average, or x402-rsi, but MACD is a named indicator whose inputs are self-defining.

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?

Implies usage by noting the required data input ('Provide values array') and which periods are optional, but offers no explicit when-to-use/when-not-to-use framing and never routes away from the closely related x402-ema, x402-moving-average, or x402-rsi siblings. Adequate but with a clear gap.

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