get_cffex_rank_table

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

Annotations already declare readOnly/idempotent/openWorld and non-destructive, so safety is covered. The description adds real behavioral context beyond them: the data availability boundary (20100416) and the daily ~16:30 refresh cadence, plus the note that the exchange publishes both product and underlying ranks. These are genuinely useful traits not in the structured fields.

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?

Purpose and source URL are front-loaded, followed by param docs and a field breakdown. The reST-style rfield listing is verbose but earns its place since no output schema exists.

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?

With no output schema and 0% param coverage, the description supplies both the two parameter semantics and a full field dictionary (rank, vol, long/short open interest and changes, symbol, var, date), plus the data-start and refresh timing. An agent has everything needed to call and interpret it.

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 0%, so the description carries the full load, and it does: date accepts YYYY-MM-DD, YYYYMMDD, or a datetime.date object and defaults to today; vars_list takes contract-product codes (RB, AL) and defaults to all commodities. That compensates almost fully for the missing schema descriptions.

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 names a specific resource ('中国金融期货交易所前 20 会员持仓排名数据明细') and the exchange, distinguishing it from the many sibling exchange rank-table tools (get_shfe_rank_table, get_rank_table_czce, get_dce_rank_table). It does not explicitly reference those alternatives, but the exchange scope makes the intent unambiguous.

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 useful operating context (data starts 20100416, updated ~16:30 per trading day, empty vars_list means all commodities), which implies usage, but never states when to prefer this tool over the SHFE/CZCE/DCE counterparts or what the note about both variety and contract ranks means for selection. Usage is implied rather than guided.

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