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

With no annotations the description carries the full burden, and it does well: it states determinism ('Same day → same answer'), forbids fabricating pillars/claims, notes 'Public · local · no API key', and frames output as 'Preview ≠ prediction'. Error handling and edge behavior are not covered.

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?

Key behavior and constraints are front-loaded, which is good, but the long middle list of eight-plus trigger phrases in mixed scripts is repetitive and padded. It earns partial credit for structure while being longer than needed.

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?

There is no output schema, and the description compensates by enumerating the return shape (time atom first line, fold-year line, baseline tone, dated sky marks, do/drop list) plus the follow-up action expected of the agent. That is largely complete for a two-parameter local tool.

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 100% for both parameters (month pattern YYYY-MM with default, locale enum), so the schema already documents them fully. The description adds no syntax, format, or default information beyond what the schema provides, matching the baseline 3 for high-coverage schemas.

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 specifies a verb+resource ('looks up a deterministic rules engine' producing a monthly flow brief with fold-year, tone, dated marks, do/drop list). That is clear and concrete. It does not, however, name or contrast against any sibling such as personal_month or sky_window, so an agent must infer the distinction.

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?

It gives an explicit, if sprawling, set of trigger phrases in both Chinese and English (这个月势能怎么样, which days to publish, etc.) that map directly to when this tool applies. No when-not condition or named alternative tool is given, so it stops short of a full routing rubric.

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