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

Annotations already declare readOnly, idempotent, closed-world, non-destructive, so the safety profile is covered. The description adds that the result is deterministic per date, which usefully reinforces the idempotent hint, and gives a credit cost. It does not describe the return shape or any auth/quota behavior beyond cost.

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 core sentence is front-loaded and terse with zero padding, and the group/cost lines are compact structured metadata. It is efficiently sized, though the one-line purpose is arguably too thin for a tool with three parameters.

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?

An output schema exists so return values need not be explained, and annotations cover the safety profile. However the description leaves the date format and sibling routing unaddressed, which are the main things an agent still needs to invoke it correctly.

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 67%: fields and precision are documented in the schema, but the date parameter has no schema description. 'per-date' tells the agent date matters but never gives a format (ISO date, timezone, etc.), so the description only partially compensates for the undocumented parameter.

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?

States a specific resource (hexagram) and a clear scope modifier (per-date, deterministic), which separates it from the random astroway_iching_throw_coins and the question-driven astroway_iching_by_question. It does not explicitly name a sibling, but 'per-date' and 'deterministic' make the purpose legible enough to distinguish it from the other I Ching tools.

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 word 'daily' and 'per-date' imply the intended use case (get the hexagram for a given day), but there is no explicit when-to-use, when-not-to-use, or routing to alternatives like astroway_iching_lookup_number or astroway_iching_with_changing_lines.

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