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

Annotations already cover readOnly/idempotent/non-destructive, so the bar is lower, and the description adds genuinely useful context the annotations cannot express: per-call cost of $0.001 USDC via x402 on Solana and an equivalent HTTPS endpoint. It does not describe the return value's shape explicitly, though the worked examples imply an integer count.

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?

Purpose is front-loaded in the first clause, followed by compact example mappings and the two practical facts (price, HTTPS endpoint). No filler sentences; every element earns its 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?

For a single-parameter read-only math tool with no output schema, the description supplies enough to call it correctly and even sample outputs to sanity-check results, plus payment/logistics details. The remaining gap is sibling disambiguation within the mcnugget family.

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%, so the description must carry the load; it does define n as the inclusive upper bound of the counted interval and restates the 0–5000 range from the schema. Nothing is said about how sums are formed (non-negative box counts, ordering irrelevant) or any edge behavior, so meaning is only partially filled in.

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 makes concrete what is being counted: integers from 0 through n that can be expressed as sums of 6, 9, and 20, illustrated with worked values (n=0→1, 6→2, 43→22, 100→79). The resource and computation are clear, but there are four sibling tools (mcnugget, mcnugget_min, mcnugget_miss, mcnugget_ways) and the description never states how this one differs from them.

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?

No guidance on when to choose this over mcnugget, mcnugget_min, mcnugget_miss, or mcnugget_ways, which are the obvious alternatives in the same family. The only usable constraint given is the input range n ∈ [0, 5000], which is already in the schema.

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