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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds genuinely non-obvious behavior: a $0.001 USDC charge per successful call via x402 on Solana, plus an equivalent HTTPS endpoint. The one missing piece is what the response payload looks like (a bare integer vs. a wrapped object), but the payment/auth disclosure is high-value context that annotations cannot express.

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?

One dense, front-loaded block: operation first, then examples, then domain, then price and endpoint. Every element serves a purpose, though three examples is arguably one more than needed for a two-parameter 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?

With no output schema, the description still makes the return type evident through worked examples, states the parameter domains, and discloses the payment requirement and alternate transport. The only gap is the mathematical definition of D(n), which matters for an agent deciding whether this is the right function at all.

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 load; it does partially by showing n as an index and m as a modulus through three n,m -> result examples, and by restating the valid ranges. However, it never defines what D(n) actually is (the Domb number), leaving the core semantic of the 'n' parameter unexplained beyond an index range.

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 states a specific computation ('D(n) modulo m') and backs it with three worked examples (D(5) mod 100 = 4, D(6) mod 1000 = 136, D(1) mod 3 = 1), so the agent can tell this returns a modular residue. It does not explicitly contrast itself with the sibling 'domb' (full value) or 'domb_term', so the differentiation is inferential rather than stated.

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 no guidance on when to choose this over 'domb', 'domb_term', 'domb_gcd', or 'domb_sum'. The domain limits (n 0-12, m 1-1,000,000) are constraints rather than usage direction, and no preconditions or exclusions are offered.

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