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

Annotations already cover read-only, idempotent, non-destructive, open-world, so the safety bar is low. The description adds genuinely non-structured context: a per-call price of $0.001 USDC via x402 on Solana and an equivalent HTTPS endpoint, which an agent needs before committing to a paid call. It does not state the literal return shape (true/false) or any rate/error behavior.

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 predicate definition, then examples, then domain bound, then commercial/pricing detail — a sound ordering with no filler sentences. The pricing and URL sentence is boilerplate but load-bearing for a paid x402 endpoint.

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 one-integer predicate with no output schema and full annotation coverage, everything needed to call it correctly is present: meaning of n, valid range, exact truth condition, worked examples, cost, and an alternate transport. The only omission — that it returns a boolean — is directly implied by 'Whether...'.

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% and the parameter is literally named 'n', so the schema alone conveys only an integer 0..1000000. The description supplies the semantic meaning (n is the number whose binary expansion is examined) and repeats the domain bound, compensating well for the undocumented parameter.

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, verifiable predicate: whether the binary expansion of n has no two adjacent 1 bits, and reinforces it with positive and negative examples (0, 1, 2, 5, 10, 21 vs 3, 6, 7). That distinguishes it semantically from fibbinary_count/fibbinary_next/fibbinary_nth, though none of those siblings are named.

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 when-to-use or when-not-to-use sentence. Given five closely named siblings (fibbinary_count, fibbinary_index, fibbinary_next, fibbinary_nth, fibbinary_sum), the description never explains that this one is the single-number boolean test rather than a count or sequence generator, leaving routing to inference from the name alone.

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