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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so safety is covered. The description adds genuinely new behavioral facts: it is a paid x402/Solana endpoint at $0.001 USDC per successful call, with a stated HTTPS alternative URL — information an agent must have before calling. No contradictions; only the return shape is left implicit.

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?

Front-loaded with the core statement, then compact supporting definitions, then boundary and payment/transport facts. Every sentence carries information; the only mild redundancy is repeating the 1..100000 bound already enforced by the schema.

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 one parameter, no output schema, and full annotation coverage, the definition supplies what matters: the index semantics, the run definition, valid bounds, and payment requirements. The one gap is that the exact return representation (e.g. an array like [2,2] vs. a length) is only inferable from the examples.

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 0%, so the description must carry the parameter, and it does: n is a 1-based index, bounded 1 to 100000, with two concrete anchor examples (index 1 → single 1, index 2 → starts two 2s). It does not state the return type (array vs. count), which is why it is not a 5.

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 concrete verb+resource relationship: given a 1-based index n, it returns the Kolakoski run containing that index. The clarification 'A run has length 1 or 2' and the two worked examples pin down what a 'run' is. It does not explicitly distinguish itself from sibling tools like kolakoski_prefix or kolakoski_sum, though 'run that contains index n' implicitly separates it from prefix/sum variants.

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 is only implied: you have an index n and you want its run. Nothing says when to prefer this over kolakoski_prefix, kolakoski_sum, or kolakoski_check, and no error behavior for out-of-range n is described beyond the stated 1..100000 bound. The domain constraint and pricing note give context but not selection guidance.

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