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

Annotations already cover read-only, idempotent, open-world, and non-destructive behavior. The description adds meaningful context beyond that: pricing ($0.001 USDC per successful call via x402 on Solana), an alternate HTTPS endpoint, and the output format change to a decimal string past 15 digits.

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 description is front-loaded with the definition and example, then moves through bounds, output format, pricing, and endpoint. Every sentence adds useful information with no redundancy.

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 appropriately explains the return-value behavior for large results (decimal string past 15 digits) and mentions the paid-call model. It is nearly complete for a pure computation tool, though it could explicitly state that smaller results are integers and distinguish from delannoy_central/delannoy_sum.

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 parameter meaning. It implicitly defines m and n as path endpoint coordinates and repeats the 0–64 bounds already encoded in the schema, but it does not explicitly describe each parameter's role or units beyond the mathematical context.

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 names the exact mathematical object (Delannoy number D(m,n)) and defines it as the number of paths with steps (1,0), (0,1), and (1,1). It does not explicitly distinguish this from siblings like delannoy_central or delannoy_sum, but the resource itself is unambiguous.

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?

It states the valid input range (m and n from 0 to 64), which implies when the tool can be called, but gives no explicit when-to-use/when-not guidance or naming of alternatives such as delannoy_central. Usage is implied rather than prescribed.

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