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

Annotations already cover safety (readOnlyHint, idempotentHint, non-destructive, closed-world), so the description's job is to say what the call yields, and it does: methods, applicable scope, data limits, and official references. With no output schema, that content inventory is the main signal an agent has about the return payload. It still does not say how the content is organized or whether it is scoped by topic.

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 sentences, front-loaded with what the tool returns, followed by the usage trigger — nothing superfluous. The Chinese restatement is a deliberate bilingual choice rather than padding, though it does double the length without adding new information.

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?

For a zero-required-parameter documentation tool with full annotation coverage, the description covers purpose, content, and when to consult it. The one gap is that it does not connect the 'topic' enum to the described content, so an agent cannot tell from the description that it can fetch just the 'limitations' or 'units' section.

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 100% and the single 'topic' parameter has a fully enumerated value list with a note that omitting it returns everything. The description adds no meaning beyond that — it never mentions the topic parameter or what each topic returns. Baseline 3 applies when the schema already does the work.

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 gives a specific verb ('Explain') and a concrete set of resources: calculation methods, scope, data limits and official references. That clearly separates it from the sibling factor-lookup and calculation tools, which return values rather than methodology. It stops short of naming a sibling explicitly, so it lands at 4 rather than 5.

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 trigger condition: 'Read this before interpreting results or combining different kinds of factors.' That is genuine when-to-use guidance tied to a recognizable agent situation. There are no explicit exclusions or named alternatives, so it is not a full 5.

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