build_book

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

With no annotations at all, the description carries the full burden, and it does disclose the return contract ({"ok": true, ...checklist} vs {"ok": false, "error": ...}) which is valuable given no output schema. It does not say where files land (the out_dir parameter is never mentioned), whether existing outputs are overwritten, or how long a build takes.

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?

Front-loaded with the outcome, then terse per-parameter lines, then the return contract. No filler, no repeated schema restatement, and the most decision-relevant information (what it produces) comes first.

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?

Given seven parameters, zero annotations, and no output schema, the definition is workable but incomplete: it explains the required inputs and return shape yet omits three optional parameters that materially change the output (out_dir, keywords, back_text) and never states that files are written to disk.

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%, and the description compensates for only part of it: manuscript_dir, cover_image, trim, and paper are explained, and the allowed trim/paper values are supplied even though the schema declares no enums. Three parameters — out_dir, keywords, and back_text — receive no mention anywhere, leaving a real gap.

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?

Names a specific verb ("Build") and enumerates the four concrete artifacts produced: Kindle EPUB, print interior PDF, full-wrap cover PDF, and KDP upload checklist. That artifact list makes it unmistakably the production tool versus the narrow helpers spine_width and list_trim_sizes.

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?

"folder containing book.json and Markdown chapters" establishes the prerequisite structure the agent must satisfy before calling, which is real usage context. It never states when not to use it or points at the siblings (e.g., list_trim_sizes) for discovering valid values, so no exclusion guidance exists.

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