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

Annotations already declare readOnlyHint=true, openWorldHint=false, destructiveHint=false, so safety is mostly covered. The description adds value beyond them: it states the return shape ('Returns each die and the total') and explains the non-obvious `hidden` behavior — the result is visible only to the agent, not the players — which the annotations say nothing about.

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 sentences: the action plus notation examples first, the return contract second. Example density is high but every token maps to a distinct notation the agent must be able to produce; nothing is redundant.

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 read-only dice roller with full parameter documentation and an explicit return statement, an agent has enough to call it correctly. Minor omissions remain: whether rolls are logged to the story/history, and any bound on dice count or modifiers (the schema caps length at 40 but the description doesn't mention limits).

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 baseline is 3; the description earns more by documenting the dice grammar beyond the schema's single '1d20+5' example — advantage ('adv 1d20+3'), disadvantage ('dis 1d20'), and drop-lowest ('4d6 drop lowest'). These notations are otherwise unstated anywhere and are essential to invoking the tool correctly.

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?

Specific verb + resource: 'Rolls dice for a Plot Speaks campaign or adventure on the server', immediately scoping the tool to the correct product context. Concrete dice-notation examples make the purpose unmistakable. No sibling is named, but none of the listed siblings could plausibly be confused with a dice roller.

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?

Usage is implied by 'for a Plot Speaks campaign or adventure' and the `hidden` example (world clock, hidden table), which hints at when a roll should be secret. But there is no explicit when-to-use vs. when-not-to-use guidance and no named alternative or prerequisite (e.g., must a story be active first?).

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