Metis · Librarian — Ask Library

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

With no annotations, description carries full burden. It discloses that the tool searches a pre-built index and returns synthesized citations, implying non-destructive read-only behavior. However, it doesn't explicitly state no side effects or permissions needed.

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?

Concise and front-loaded: one sentence for purpose, minimal parameter list. No filler, but could be slightly more structured.

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 sibling tools and presence of output schema, description covers primary use case, dependency on index, and scope variants. Lacks details on return format but output schema handles that.

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%, but the description's 'Args' section explains each parameter: question, top_k (default 5), and scope with concrete options (default, ph_library). Adds significant value beyond bare schema.

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 clearly states the tool answers a question using the user's indexed PDF library via PaperQA2, returning a synthesized answer with citations. It distinguishes from sibling tools like search_library by focusing on synthesis rather than raw retrieval.

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?

Provides guidance on prerequisite (build index first with index_library_pdfs) and explains scope options. Could be stronger by explicitly listing when not to use, but gives adequate context.

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