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

With no annotations present, the description carries the full burden of disclosing behavior, and it discloses nothing — no return format, no side effects, no edge cases, no mention of what input the check operates on. The description is information-fee.

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 two words — but this is under-specification, not effective coniseness. It contains zero information beyond the name and thus fails to earn any of the sentences it uses.

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 output schema, no annotations, and a zero-param schema, the description must explain what the tool does, what to pass, and what comes back — it does none of these. An agent cannot safely select, invoke, or interpret the result of this tool.

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 0 parameters with 100% (vacuous) coverage, so there is no parameter meaning for the description to add; a baseline of 4 applies per rubric. The only caveat is that a predicate tool with zero inputs is anomalous, and the description could have claried this, which tempers full credit.

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 'Is Triangular: Is Triangular' is a pure tautology — it merely restates the tool name and gives no content whatsoever. It never states what the tool checks (e.g., whether a number is a triangular number), what a triangular number is, or what input/output to expect.

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. Among hundreds of siblings consisting largely of is-* predicates (is-prime, is-abundant, is-perfect) and triangle-related tools (triangle-area, triangular-series), the description provides no basis for selecting this one over any other.

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