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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description usefully adds the credit cost and the return range ('decimal between 0 and 1'), which annotations do not convey. It says nothing about edge cases such as invalid inputs or rounding/precision of the returned decimal.

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?

Two compact sentences: the operation and formula first, then the return value and cost. Nothing is padded, though the cost parenthetical could arguably be a separate structured field rather than description prose.

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 three-parameter math tool with no output schema, the description covers the computation and the result format adequately. However, the unexplained role of the required target_value parameter (absent from the given formula) is a real completeness gap an agent could trip over.

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 100%, so all three parameters (including the 1..num_sides constraint on target_value) are already documented in the schema, making 3 the baseline. The description does add that num_sides and num_rolls feed the formula, but it creates ambiguity by never explaining target_value, which the stated formula does not actually use.

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 gives a specific verb ('Calculates') plus a precise resource (probability of consecutive identical rolls on an N-sided die) and even states the exact formula. It does not, however, differentiate itself from the sibling dice_roll_probability, so an agent must infer which of the two to pick.

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?

There is no when-to-use guidance, no exclusions, and no pointer to the closely related sibling dice_roll_probability. The only extra context is a cost note, which is billing information rather than selection guidance.

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