list_libraries

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively describes the tool's behavior by specifying the return format ('list of archives with their kind, metadata, and aggregate capabilities') and implying it's a read-only inventory operation (no destructive actions mentioned). However, it lacks details on potential errors, rate limits, or authentication requirements, which are minor gaps.

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 front-loaded with the core purpose in the first sentence, followed by details on returns and usage guidance. Every sentence earns its place: the first explains what it does, the second details the output, and the third provides critical context on when to use it. There is no wasted text, and it's structured for clarity.

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 tool's complexity (simple inventory with 0 parameters) and lack of annotations/output schema, the description is largely complete. It covers purpose, output details, and usage context. However, it doesn't specify the exact structure of the returned list or error handling, which are minor omissions for a tool of this 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?

The tool has 0 parameters, and schema description coverage is 100%, so no parameter documentation is needed. The description appropriately focuses on output semantics, explaining what information is returned (e.g., archive kinds, metadata, capabilities like 'plan_route'). This adds value beyond the empty input schema, justifying a score above the baseline of 3.

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 specific action ('Inventory') and resource ('ZIM archives this server can read'), distinguishing it from sibling tools like get_article, get_main_page, and search by focusing on system inventory rather than content retrieval. It explicitly mentions what is returned ('list of archives with their kind, metadata, and aggregate capabilities'), making the purpose unambiguous.

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 explicit guidance on when to use this tool: 'Call this first so you know what sources and tools are available.' This indicates it should be used as an initial step to discover available resources before invoking other tools, clearly differentiating it from siblings that perform content operations.

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