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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds useful scope detail (owned or shared libraries) and the backing endpoint, but stays silent on pagination behavior and return shape.

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 tight sentences with the core purpose and scope front-loaded, followed by the API reference. No 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?

For a simple read-only list tool whose parameters are fully described in the schema and whose safety profile is covered by annotations, the description is nearly sufficient. Only the lack of explicit sibling routing keeps it from being fully complete.

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 four optional params (page, page_size, search, page_token) are already fully documented in the schema. The description adds no syntax, defaults, or interaction detail beyond what the schema provides.

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?

States a specific verb (List) and resource (RAG document libraries) plus the ownership scope ('you own or shared with you'). It does not, however, name the closest sibling mistral_list_library_documents, leaving the agent to infer the library-vs-document 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 scope clause implies when the tool applies (surfacing libraries accessible to the caller), but there is no explicit when-to-use or when-not-to-use guidance relative to siblings like mistral_get_library or mistral_list_library_documents.

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