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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context: it is an estimate rather than a guarantee, ranges are preserved rather than collapsed, and it does not look up an account. It stops short of stating determinism guarantees or the shape of the range/estimate output, but for a read-only calculator this is solid added value.

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 operation type and the core use case, and each following sentence adds a distinct fact (coverage list, range preservation, estimate caveat, exclusions). The leading 'CALCULATION.' stub is slightly redundant with the name, and the coverage list is dense, but nothing is wasted.

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 an output schema present, return values need not be explained, and the description covers trigger, scope, caveats, and exclusions. An agent has everything needed to choose this over its siblings and call it 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?

Schema description coverage is 100% and each parameter already documents its meaning, including the note that amount_usd is not a Snap pay rate and that tax_info_verified does not query an account. The description restates the cash-out-minimum comparison and verification flag without adding syntax or interpretation beyond the schema, so the baseline 3 applies.

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+resource ('date-by-date timeline of Snap's payout steps from a credited date') and enumerates the exact stages covered (Pending to Available, cash-out minimum, taxpayer verification, Payout Portal). It also explicitly names the sibling tools it is not, so it is distinguishable without opening any schema.

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?

Gives an explicit trigger ('Use this when you need a date-by-date timeline...') and explicit exclusions with named alternatives ('Do not use it to score eligibility (check_eligibility) or to list every rule (get_monetization_requirements)'). This is exactly the when/when-not/alternative pattern.

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