Calibre MCP Server

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

No annotations are provided, so the description carries full burden. It mentions a 'limit' parameter with a default and 'sentence_aware' behavior, but doesn't disclose critical behavioral traits: whether this is a read-only operation, potential rate limits, authentication needs, error conditions, or what happens if book_id is invalid. For a tool with 5 parameters and no annotations, this is insufficient.

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 extremely concise—four sentences total, with the first stating the purpose and the next three explaining key parameters. Every sentence adds value, and it's front-loaded with the core function. No wasted words or 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?

Given 5 parameters with 0% schema coverage, no annotations, and no output schema, the description is incomplete. It doesn't explain the return format (e.g., text structure, error responses), doesn't cover all parameters, and lacks behavioral context. For a content retrieval tool with multiple parameters, this leaves significant gaps for an AI agent.

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%, so the description must compensate. It explains three parameters (limit, offset, sentence_aware) with some semantics (e.g., 'adjusts to nearest sentence boundary'), but doesn't cover 'book_id' (required) or 'library_name'. Since it documents 3 of 5 parameters partially, it adds value but doesn't fully compensate for the schema 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?

The description clearly states the verb 'Retrieve' and resource 'text content of a book', making the purpose evident. However, it doesn't explicitly differentiate from sibling tools like 'get_book_details' or 'search_book_content', which likely retrieve different aspects of books. The purpose is clear but lacks sibling distinction.

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 provides no guidance on when to use this tool versus alternatives. With siblings like 'get_book_details' (likely metadata) and 'search_book_content' (likely search within content), there's no indication of when this retrieval tool is appropriate versus those. No prerequisites or exclusions are mentioned.

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