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

Annotations already declare readOnly, idempotent, non-destructive, open-world behavior; the description adds exactness, input validation rules, a per-success price, and the HTTPS endpoint. It does not describe the return value or error response format.

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 operation is front-loaded in the first clause, followed by only relevant constraints, price, and endpoint. There is no filler.

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 three-parameter paid computation with no output schema, the description covers the operation, valid domain, cost, and HTTPS alternative. The main omission is return type/format, which is not documented in an output schema.

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 coverage is 0%, so the description must carry parameter meaning: it maps base, exp, and mod via the formula and adds constraints for exp (non-negative), mod (>=1), and integer formatting (no leading zeros, <=200 digits). It leaves some signed-string nuances to the schema patterns.

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 formula 'base^exp mod m, exact' states the operation precisely, and the non-negative exponent and modulus >= 1 constraints clarify scope. It does not distinguish itself from the sibling power_mod, so it stops short of 5.

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 gives validity conditions (non-negative exponent, modulus at least 1, negative exponent rejected) that imply when the tool is appropriate. It does not name alternative siblings such as power_mod or mod_inv or explicitly compare use cases.

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