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

Annotations already declare readOnly, idempotent, and non-destructive, so the description's added value is the commercial and transport context: $0.001 USDC per successful call via x402 on Solana, plus an equivalent HTTPS POST endpoint. The worked example (L0..L5 = 28) also confirms the return shape is a single integer.

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 definition leads with the operation and its bounds before the example, formula, price, and endpoint. Every sentence is functional; the pricing/endpoint clause is slightly commercial in tone but relevant to actually invoking the tool.

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?

For a two-parameter pure computation with no output schema, the description supplies the domain, the bounds, the ordering constraint, a worked example, and a closed-form identity, so an agent knows exactly what it will get back and when a call is invalid.

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 semantics, and it does: lo and hi are inclusive Lucas indices bounded to 0-4096, with the ordering constraint lo <= hi. Redundancy with the schema's min/max is minor; the inclusive semantics and the identity L(hi+2) - L(lo+1) are genuinely additive.

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 and resource: the sum of Lucas numbers over an inclusive index range. It is unambiguously distinguishable from siblings like lucas, lucas_index, lucas_mod, and leonardo_sum, which compute a term, index, modular value, or a different sequence.

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?

It defines the operating envelope (lo must not pass hi; each index runs 0-4096), which prevents invalid calls, but it gives no explicit when-to-use guidance versus sibling sequence-sum tools. Usage is implied by the math rather than stated as selection criteria.

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