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

Annotations already declare readOnly, idempotent, non-destructive, openWorld. The description adds genuinely new operational context: a price of $0.001 USDC per successful call (x402, Solana) and a parallel HTTPS endpoint, which the agent needs in order to invoke it at all.

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 definition and worked examples before the operational details (range, price, endpoint). Slightly dense and the pricing URL sentence is appended without separation, but no sentence 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?

There is no output schema, so the description supplies return-value evidence via three worked examples that imply a scalar integer result. For a one-parameter, read-only math utility this is nearly everything an agent needs; only explicit sibling routing is missing.

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 parameter is undocumented in the schema, so the description must carry the load — it states 'n runs from 0 to 11' and anchors the semantics with concrete results (n=0→1, n=2→79, n=5→853530), letting the agent sanity-check a call.

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 precise verb+resource: 'the sum of the Apery numbers A(0) through A(n)', which distinguishes it from the sibling apery_term (single term) by the word 'sum'. It never explicitly names apery, apery_mod, or apery_prime as alternatives, so sibling differentiation is only implicit.

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?

The description defines what is computed and constrains n to 0..11, but gives no guidance on when to pick this over apery, apery_term, apery_mod, or apery_prime. No prerequisites or exclusion conditions are stated beyond the schema's own min/max.

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