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

Goes well beyond the readOnly/idempotent annotations: discloses deterministic remainder distribution, ISO 4217 minor-unit exponent handling with JPY/KWD examples, explicit rejection of metals and XXX, and the $0.05 x402/USDC-on-Base payment requirement. The x402 cost disclosure is exactly the kind of operational context annotations cannot carry.

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 purpose and progresses logically to mechanics, currency handling and price. Slightly dense with some restatement of the rule names already enumerated in the schema, but no filler.

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?

Covers inputs, edge cases (zero- and three-decimal currencies, rejected metals/XXX), determinism, and pricing. With no output schema, it would be stronger if it sketched the return shape (e.g. a list of per-share amounts), which is the one remaining gap for a compute tool.

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 100%, so the baseline is 3; the description adds real meaning by explaining what the remainder rules do and why currency drives minor-unit exponent. It loses a point for naming only 'largest-remainder, first-wins or last-wins' while the enum also contains 'round-robin', so the prose is incomplete relative to the 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?

States a specific verb and resource ('split a money amount into shares') plus the defining constraint ('without losing or inventing a cent'), which no sibling tool covers. An agent can distinguish it from currency_lookup or any other sibling immediately.

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?

Explains the two usage modes ('divide evenly into N parts, or by a list of ratios') and the conditions under which each applies. It does not name alternatives or exclusions, but no sibling overlaps this function, so the context is sufficient.

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