list_my_books

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the bar for transparency is lower. The description adds value by specifying the ordering (most-recently-updated first) and the exact return format ({ count, books[] } with fields). It also discloses a required authentication token and its source. The only gap is no mention of pagination behavior beyond the limit parameter, but given the richness otherwise, 4 is warranted.

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 concise at roughly 3 sentences (slightly more with the auth note). It front-loads the purpose and ordering, then return format, then usage guidelines, then auth notes. Every sentence earns its place. There is no redundancy or filler.

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 the low complexity (2 optional params, no output schema), good annotations, and rich description, the tool is well-covered. The description explains the return format, usage context, auth requirements, and ordering. A minor gap is the lack of mention of pagination continuation (e.g., how to get next page beyond limit). But overall it is very complete for this tool's simplicity.

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 the baseline is 3. The description does not add additional parameter details beyond what the schema provides (the schema already documents limit and status including enumerated values and defaults). The description mentions optional filtering by shelf in passing, but that maps to the already-documented status parameter. The description adds no new semantic value for the parameters.

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 the tool lists books on the authenticated user's shelves with a clear ordering (most-recently-updated first). The title annotation 'List my library' reinforces the purpose. The verb 'list' combined with the resource 'books on the authenticated user's shelves' is specific and distinguishes it from siblings like search_books which targets the public catalog.

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 an explicit 'When to use' section that indicates when to use this tool (browse or enumerate the user's library, optionally filtered by shelf). It also names two clear alternatives: search_my_library for finding a specific title within the library, and search_books for the public catalog. This directly addresses usage context and sibling differentiation.

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