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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered; the description adds real value beyond that with pricing ($0.001 USDC per successful call via x402 on Solana) and a documented HTTPS fallback endpoint. It stops short of describing failure behavior for out-of-range n or error/response semantics.

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?

Four tight clauses front-loaded with the definition, then examples, then domain, then cost/transport. No filler; the only arguable redundancy is restating the 0-11 range already enforced by the schema's minimum/maximum.

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 and no output schema, the description supplies example outputs that effectively stand in for a return-value spec, plus pricing and transport details. The remaining gap is that 'D(n)' is never expanded, which matters for an agent unfamiliar with the Domb sequence.

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 coverage is 0%, so the description must carry the parameter burden, and it does: n is the index into the sequence, bounded 0-11, with worked values (n=0→1, n=1→4, n=6→64) that let an agent sanity-check output. It repeats the schema's min/max but goes beyond it by anchoring n to concrete results.

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 precise operation ('greatest common divisor of D(n) and D(n+1)') with a concrete parameter domain, so an agent knows exactly what is computed. It never defines what D(n) is (Domb numbers), and it does not explicitly contrast itself with siblings like domb, domb_term, or franel_gcd, so differentiation is only implicit.

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?

The valid range 'n runs from 0 to 11' plus sample values give enough context to call it correctly, but there is no guidance on when to pick this over domb, domb_sum, domb_term, or the other gcd-family tools. Usage is implied by the single-argument nature rather than stated.

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