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

Annotations already declare readOnlyHint and idempotentHint. The description adds valuable context: determinism given dates and the bias toward rarer deities with higher Cosmic Score tiers. These traits are not in annotations and help the agent understand expected behavior without side effects.

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 concise sentences, front-loaded with the primary action and resource. Every clause adds value: the collection size, determinism, bias mechanism, and return fields. No redundant phrasing or 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?

The description lists return fields and hints at the deterministic inputs, but the meaning of the required year/month/day parameters is not explicitly clarified. Since there is no output schema, the description should more thoroughly explain how these inputs map to the deterministic draw. Overall adequate but with a notable gap in parameter semantics.

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 only 25% (only the optional 'date' parameter has a description). The description mentions 'birth date, current date' as deterministic inputs, but it does not explicitly map the required year/month/day parameters to a birth date, leaving ambiguity about what each parameter represents. With low schema coverage, the description should compensate more clearly.

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 clearly states the action 'Draw today's deity card' with a specific resource (1,069-deity collection), mentions deterministic behavior, and lists return fields (deity, mythology origin, tier, message). It is distinct from siblings like get_deity_lore or get_deep_reading, which focus on lore or detailed readings.

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 implies daily use with 'today's deity card' and mentions determinism based on birth date and current date, but it does not explicitly state when to use this tool versus alternatives or when not to use it. No exclusions or comparisons to siblings are provided.

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