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

Annotations already declare read-only, idempotent, non-destructive, and open-world behavior. The description adds valuable context beyond annotations: cost ($0.001 USDC per successful call via x402 on Solana), an alternative HTTPS endpoint, index bounds, and a worked example. It does not mention rate limits or auth beyond payment.

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 definition is front-loaded with the core purpose, followed by a concrete example, constraints, and payment/access details. Every sentence contributes useful information, though the pricing and endpoint sentences are peripheral but relevant for a paid API.

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 simple two-parameter read-only computation with no output schema, the description covers parameter meaning, bounds, validity constraint, a sample result (implying return value), and access/payment details. Annotations already handle safety profile, so nothing essential 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?

With schema description coverage at 0%, the description compensates by explaining that lo and hi are inclusive indices in the Tribonacci sequence, that lo must not exceed hi, and that each index runs 0–4096. This adds clear meaning beyond the bare numeric 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: 'The sum of Tribonacci numbers from lo through hi inclusive.' This clearly defines the operation and domain, but does not explicitly contrast with sibling tools like tribonacci (single term) or trib_index, leaving sibling differentiation 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?

Provides only the constraint 'lo must not pass hi' and index bounds, with no guidance on when to use this tool versus alternatives such as tribonacci or trib_step. No explicit usage context or exclusions are given.

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