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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the description's added value is the operational context: n is bounded to 1–1000000, each successful call costs $0.001 USDC via x402 on Solana, and an equivalent HTTPS endpoint is given. Cost and payment constraints are exactly the kind of behavior an agent needs and are not present in any structured field.

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 comes first, followed by compact illustrative examples, then the input range, then pricing and an alternate endpoint. Nothing is padded, though the pricing/URL tail is prose rather than structured and slightly dilutes the front-loading.

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 must imply the return value; 'how many digits... uses' reasonably conveys a single integer count, and the examples make the counting convention verifiable. An explicit statement of the return type and maximum possible output would close the remaining gap.

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% and the single property n carries no description, so the description must carry the weight. It states the domain (1 to 1000000) and, through the example list, makes clear that n is the integer whose factorization digit count is being measured. It does not restate the type, but the semantics are unambiguous.

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 opens with a specific definition of the computed quantity (digit count of the written prime factorization, exponents of 1 omitted) and backs it with worked examples (1→1, 4→2, 12→3, 16→2, 125→2) that pin down the exact convention. It is clear what the tool does, but it never contrasts itself with the many nearby number-theory siblings such as big_omega, little_omega, sopfr, or radical, which also operate on prime factorizations.

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 statement of when to reach for this tool versus the abundant alternatives in the same family. The examples and the n range imply the use case, but nothing tells an agent under what conditions this is the right choice over, say, big_omega or factor_concat.

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