set_metadata

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

Clearly states that field values are REPLACED (behavioral trait). Provides details on how tags and identifiers should be formatted. Since no annotations exist, description handles transparency well, though it could mention input validation limits.

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?

Description is well-structured with a brief intro, a bullet list of supported fields, important notes, and an Args section. It is relatively concise but the list of fields could be more compact.

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 no annotations, description covers purpose, supported fields, replacement behavior, and format requirements. Output schema exists (context signal) so return values are not needed. Slight lack of guidance on error handling or prerequisite conditions.

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 coverage is 0%, so description must compensate. It explains book_id is 'the Calibre book ID' and fields is a dict mapping field names to values with examples. This adds significant meaning beyond schema property names.

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?

Description specifies verb 'set' and resource 'metadata fields for a book' with a clear list of supported fields. It distinguishes from siblings like 'get_book_info' and 'set_custom_column' by focusing on standard metadata.

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?

Description explains when to use (setting standard metadata) and provides usage examples for tags and identifiers. However, it does not explicitly state when not to use or mention alternatives like set_custom_column for custom fields.

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