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

With no annotations, the description carries the full behavioral burden: it does disclose a concrete billing trait ('1 credit' per call), which is genuinely useful cost context. However, it says nothing about result size/pagination (limit default 30), whether results are ranked, or what a ledger entry contains, so the behavioral picture remains partial for a tool that presumably returns metrics.

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?

It is a single compact line with the resource and filter axes front-loaded, followed by the credit cost. Repeating the enum values is somewhat redundant against the schema, but it aids scanning and wastes little space.

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 annotations and no output schema for a 4-parameter filtered query, the description should signal what a ledger row returns (word metrics? credit ledger?) and whether results are ordered. It also omits any sibling differentiation, so an agent has to guess both the return shape and when this tool is the right choice.

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 `site` parameter is documented), and the description partially compensates by listing the enum values for type and direction. But those values are already in the schema enums, so the added value is small, and the `limit` parameter has no explanation in either place (max? does it truncate?).

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 states a clear verb (词账本查询 / query the word ledger) and enumerates the filter dimensions (type, direction, site matching), which matches the four schema parameters. It does not differentiate from siblings such as ledger_pulse or trends_rising, so an agent cannot tell from the description alone why it would pick this ledger query over the pulse/rising feeds.

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 explains how to filter but never says when to use this tool versus ledger_pulse, trends_rising, or site_radar_latest. The only usage-like signal is the price line ('1 credit'), which is cost context rather than when-to-use guidance; no prerequisites or exclusions are given.

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