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

No annotations exist, so the description carries the full burden of behavioral disclosure, and it discloses nothing. An agent cannot learn what the tool computes, what inputs it expects, what its output looks like, or why the input schema is empty even though Heron's formula requires three side lengths.

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 short, but for the wrong reason — it is under-specified, not concise. 'Triangle Heron' appears twice in a single redundant phrase that carries no information beyond the tool name itself.

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, an empty input schema, and a one-line tautological description, every informational burden falls on the description and it fails all of them. An agent cannot tell what this tool does, when to invoke it, or what result to expect.

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?

The schema has zero parameters, which normally earns a baseline of 4, but here the schema conflict is glaring: a Heron's formula tool logically requires triangle side inputs yet defines none. The description adds no meaning to explain how input is supplied, leaving the agent unable to construct a valid invocation.

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 'Triangle Heron: Triangle Heron' is a pure tautology — it restates the tool name without adding any verb or explanation of what the tool computes. It gives no indication that this computes a triangle's area via Heron's formula, and offers nothing to distinguish it from sibling tools like x402-triangle-area.

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 zero guidance on when to use this tool. No context, no exclusions, and no mention of alternatives, despite a large set of overlapping geometry siblings (x402-triangle-area, x402-triangle-circumradius, x402-triangle-inradius) that an agent would need help routing between.

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