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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds materially useful behavior context beyond annotations: per-call pricing in USDC via x402 on Solana and an equivalent HTTPS endpoint. It does not contradict the annotations.

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 is front-loaded and the examples, range, price, and HTTPS alternative each add useful information. It is a bit example-heavy at five values, but nothing is irrelevant or structurally wasteful.

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 low-complexity, single-parameter math lookup with rich annotations and no output schema, the description covers indexing, range, examples, pricing, and alternate access. It does not explicitly state the return type, but the 'nth fibbinary number' phrasing and examples make the output sufficiently clear.

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 compensate for the single parameter n. It does so by defining the indexing convention ('counting from 1, with 0 in position 1'), giving five concrete nth-value examples, and restating the 1-to-5000 range. This adds clear meaning beyond the bare integer schema.

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 clearly states that the tool returns the nth fibbinary number and defines the 1-based indexing with concrete examples. It distinguishes the operation from a count or inverse lookup by emphasizing 'nth' and giving sample values, though it does not explicitly name or contrast the sibling tools fibbinary, fibbinary_count, fibbinary_index, or fibbinary_next.

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 n range of 1 to 5000 and the worked examples imply when the tool applies, but there is no explicit guidance on when to use this tool versus alternatives such as fibbinary_index or fibbinary_next. The usage is inferable but not stated.

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