books_by_topicBrowse books by subject or topic (e.g., 'science fiction', 'philosophy'). Returns matching titles, authors, and IDs.
| Name | Required | Description | Default |
|---|---|---|---|
| topic | Yes | Topic or subject keyword to filter books by (e.g. "science", "love", "history"). |
| Name | Required | Description | Default |
|---|---|---|---|
| books | Yes | List of books matching the topic | |
| count | Yes | Total number of books matching the topic | |
| topic | Yes | Topic/subject filter used |
Changes observed during successful MCP inspections.
Output schema / (root)Previous value: -nullNew value: +{
+ "properties": {
+ "books": {
+ "description": "List of books matching the topic",
+ "items": {
+ "properties": {
+ "authors": {
+ "description": "List of book authors",
+ "items": {
+ "properties": {
+ "birth_year": {
+ "description": "Author birth year or null",
+ "type": [
+ "number",
+ "null"
+ ]
+ },
+ "death_year": {
+ "description": "Author death year or null",
+ "type": [
+ "number",
+ "null"
+ ]
+ },
+ "name": {
+ "description": "Author name",
+ "type": "string"
+ }
+ },
+ "required": [
+ "name",
+ "birth_year",
+ "death_year"
+ ],
+ "type": "object"
+ },
+ "type": "array"
+ },
+ "download_count": {
+ "description": "Number of downloads",
+ "type": "number"
+ },
+ "formats": {
+ "additionalProperties": {
+ "type": "string"
+ },
+ "description": "Available download formats and URLs",
+ "type": "object"
+ },
+ "id": {
+ "description": "Project Gutenberg book ID",
+ "type": "number"
+ },
+ "languages": {
+ "description": "Languages the book is available in",
+ "items": {
+ "type": "string"
+ },
+ "type": "array"
+ },
+ "subjects": {
+ "description": "Subject tags for the book",
+ "items": {
+ "type": "string"
+ },
+ "type": "array"
+ },
+ "title": {
+ "description": "Book title",
+ "type": "string"
+ }
+ },
+ "required": [
+ "id",
+ "title",
+ "authors",
+ "languages",
+ "subjects",
+ "download_count",
+ "formats"
+ ],
+ "type": "object"
+ },
+ "type": "array"
+ },
+ "count": {
+ "description": "Total number of books matching the topic",
+ "type": "number"
+ },
+ "topic": {
+ "description": "Topic/subject filter used",
+ "type": "string"
+ }
+ },
+ "required": [
+ "count",
+ "topic",
+ "books"
+ ],
+ "type": "object"
+}Input schema / examplesAdded value: +[
+ {
+ "topic": "science fiction"
+ },
+ {
+ "topic": "philosophy"
+ }
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safe read-only nature is covered. The description adds that it returns matching titles, authors, and IDs, but does not disclose behaviors like ordering, no-results handling, or topic matching semantics, providing only modest value beyond annotations.
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?
The description is a single, front-loaded sentence with concrete examples and return fields. It contains no unnecessary words, making it highly scannable and efficient.
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-only browse tool with comprehensive schema annotations and an output schema, the description covers the core purpose and return content. It could mention result ordering or matching behavior, but the low complexity and existing schema make this reasonably complete.
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?
The input schema already fully documents the single 'topic' parameter (100% coverage) with a description and examples. The tool description gives additional examples ('science fiction', 'philosophy') but does not add substantive meaning beyond the schema, so the baseline score of 3 is appropriate.
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 clearly identifies the action ('Browse books by subject or topic') and the resource (books), with concrete examples. It does not explicitly contrast with sibling tools like search_books or popular_books, so it lacks explicit sibling differentiation.
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?
The description implies the tool is for topic-based lookup ("by subject or topic") but provides no explicit when-to-use instructions or alternatives. Sibling tools exist (e.g., search_books, popular_books) but are not mentioned, leaving the agent to infer when this tool is preferred.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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