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

Annotations already declare destructiveHint=true and idempotentHint=true, and the description adds critical behavioral context: it discards rating and progress, not just removes the shelf entry. This goes beyond the annotation's generic destructive flag and tells the agent exactly what data is lost. It doesn't mention irreversibility explicitly, but 'discarding' strongly implies it.

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?

Two sentences, zero filler. The primary action and its consequence are front-loaded, and the alternative routing is in the second sentence. Every word earns its place.

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 single-parameter destructive tool with no output schema, the description covers the action, the data loss consequence, and the alternative. The only minor gap is not stating that the operation is irreversible or that it requires the signed-in reader's own library, though 'signed-in reader's shelves' implies the latter.

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 doesn't explain what workId is or how to obtain it, but the parameter name is self-explanatory and the description's context ('a book') implies workId identifies the book. The description adds no format or source guidance beyond the schema's minLength:1, so a baseline 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 states a specific verb ('Take... off'), the resource ('signed-in reader's shelves'), and the full effect ('entirely, discarding their rating and progress'). It clearly distinguishes this from moving a book to a different shelf, which is the key 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 explicitly says when to use this tool vs the alternative: 'To move it to a different shelf instead, call add_to_library with a new readingStatus.' This is a clear when/when-not with a named alternative.

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