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

Annotations already establish read-only, idempotent, open-world, and non-destructive behavior. The description adds material context beyond that: a $0.001 USDC x402/Solana price per successful call, an HTTPS endpoint, and the a+b cap. It does not explicitly say the tool returns J(a+b), but the formula strongly implies it.

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 rule and formula are front-loaded, followed by the cap and then pricing/endpoint details. It is compact and each sentence carries useful information, though the pricing and endpoint clause is slightly appended rather than integrated.

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 two-parameter math computation with no output schema, the description gives the identity, the key domain constraint, the cost, and an alternate HTTPS endpoint. The main omission is an explicit statement that the return value is the Jacobsthal number J(a+b).

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 assigns a and b roles in the L/J formula and adds an important a+b <= 8192 constraint that the schema's per-parameter maxima do not express. It still does not explicitly define what J and L denote or spell out that a and b are Jacobsthal indices.

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 operation ('Jacobsthal addition rule') and supplies the exact identity, making it clear the tool computes J(a+b) from two indices. It does not explicitly distinguish this from siblings like jacobsthal, jacobsthal_sum, or jacobsthal_lucas, so sibling differentiation is only implied.

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 only usage condition given is the 'a+b must be at most 8192' cap. There is no guidance on when to choose this over jacobsthal, jacobsthal_sum, or jacobsthal_power despite many closely related siblings.

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