tnd_preview_book

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 the returned data shape (author, intro, counts, latest chapter), which is genuinely useful given there is no output schema, and 读取 implies a read-only operation. It says nothing about permissions, whether the source is remote vs local, rate limits, or what happens with an invalid or missing book_id.

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?

One front-loaded sentence with no filler; every listed field maps to real returned data. It is slightly run-on as an enumeration, but nothing is wasted and the key action leads the sentence.

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 one-parameter read tool with no output schema, outlining the return contents is exactly the compensating information an agent needs. The remaining gap is sibling disambiguation against tnd_get_book_status and tnd_get_chapters, which the description never addresses.

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 book_id parameter already carries the note '数字书籍 ID'. The description adds no format, source, or validity information beyond the schema, so the documented-baseline of 3 applies.

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 verb (读取) and resource (一本书) and enumerates exactly what is returned: details, author, intro, chapter count, word count, latest chapter title. That is far clearer than the bare tool name. It does not, however, distinguish this from siblings like tnd_get_book_status or tnd_get_chapters, which could plausibly return overlapping fields.

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?

There is no explicit when-to-use guidance, no prerequisites, and no named alternative. The word 'preview' hints at a pre-download inspection step, but an agent facing 23 sibling tools gets no statement of when to call this instead of tnd_get_book_status or tnd_get_chapters.

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