update_library_book

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

Annotations declare readOnlyHint=false and destructiveHint=false, but the description adds critical behavioral context: partial update semantics ('only the fields you pass change'), special side effects (current_page creates a log entry for get_reading_stats, rating/review publish publicly), error behavior (404 if not found), and return value (updated row). This far exceeds annotation coverage.

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, well-structured paragraph of 4-5 sentences. It front-loads the core purpose, then layers special behavior, return value, error condition, usage guidance, and auth requirement. Every sentence adds distinct value with no redundancy.

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?

Despite no output schema, the description covers: partial update semantics, special behaviors for specific fields, return value ('Returns the updated row'), error condition (404), prerequisites (book must exist), usage guidance with sibling references, and authentication requirement (SANSFICTION_TOKEN). For a tool with 7 parameters and complex side effects, this is 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?

Schema description coverage is 100% so baseline is 3. The description adds value by stating 'Supply any subset — only the fields you pass change,' which clarifies the partial update model. It also explains the special semantics of current_page, rating, and review beyond their schema descriptions. One point above baseline for this added clarity.

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 opens with a specific verb+resource: 'Update one or more fields of a book already in the library.' It distinguishes from sibling tools by naming add_book_to_library and remove_book_from_library, and mentions that current_page feeds get_reading_stats, making its role clear against other library tools.

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?

Explicit guidance: 'When to use: change fields or log progress for a book ALREADY on a shelf. Add it first with add_book_to_library; remove it with remove_book_from_library.' Also notes error 404 if book not in library, reinforcing prerequisite. No ambiguity.

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