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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so the safety profile is covered. The description adds genuinely new behavioral context: a per-call price of $0.001 USDC via x402 on Solana, charged only on success, plus an equivalent HTTPS endpoint — details an agent needs before invoking a paid tool.

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 sentences, front-loaded with what the tool returns and how the string is ordered, then examples, then constraint and payment. Only the range restatement is redundant with the schema; the pricing and endpoint sentences earn their place.

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 carries the burden of explaining the return value, and it does via the worked examples (1→1, 4→101, 100→1000010100). Combined with the covered safety annotations and single bounded input, the agent has what it needs to call this correctly.

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?

There is one parameter with 0% schema description coverage, so the description must compensate. It does state the domain of n (1 to 1000000000000), but that merely repeats the schema's min/max, and the examples imply rather than explain that n is the integer whose representation is computed.

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 verb+resource: it returns the Zeckendorf bit string of n, and pins down the exact bit ordering ('from the largest used Fibonacci index down to F2') with worked examples. That is enough to distinguish it in spirit from siblings like zeckendorf and zeckendorf_sum, though it never names them explicitly.

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?

Usage is only implied: the format examples suggest you use this when you want the binary/Fibonacci-base representation of a number. There is no explicit statement of when to prefer this over zeckendorf or zeckendorf_sum, and no exclusions or prerequisites beyond the numeric range.

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