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

The annotations already declare that this is a safe, read-only, non-destructive, open-world operation, so the description does not need to establish the safety profile. It adds two pieces of genuinely new behavioral information: the result includes the individual die outcomes, the die count, and the sum, and each call costs 1 credit. It says nothing about limits (max dice or sides), invalid notation handling, or failure modes, so the description does not fully cover the behavior beyond the annotations.

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 a compact two-sentence block that front-loads the capability and then states the output shape and cost. The only waste is the 'Dice Roller: Dice Roller is...' naming redundancy, which repeats the title without adding information.

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-optional-parameter tool with a full output schema, full schema coverage, and declared annotations, the description covers the necessary ground: what it does, what notation it accepts, what it returns, and a credit cost. Only edge-case behavior for malformed notation or large dice counts is missing, which is minor at this complexity.

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 the schema already documents both parameters, including XdY notation examples and the note that the modifier can be negative. The description only repeats the notation examples ('3d6 or 2d20 with optional modifiers') and adds no syntax constraints beyond what the schema provides, so the baseline of 3 applies.

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 states a specific verb and resource: it 'simulates RPG dice rolls' using 'standard notation like 3d6 or 2d20 with optional modifiers.' An agent can distinguish it from nearby randomness tools (CoinFlipper, LotteryNumberGenerator, RandomDataGenerator) because the RPG-dice framing is explicit. It opens by restating the name and title, which weakens it slightly.

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 description gives no guidance on when to call this tool versus alternatives, whether it should be used for simulation, game logic, or randomization, and lists no exclusions or prerequisites. The use case can be inferred from the words 'RPG dice rolls,' but that inference is left entirely to the agent.

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