list_librariesList all supported documentation libraries and filter by category to quickly find the official docs you need for any framework.
List all 45+ supported documentation libraries, optionally filtered by category.
| Name | Required | Description | Default |
|---|---|---|---|
| category | No | Optional category filter string. |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the burden of behavioral disclosure. It fully describes the enumerative, non-mutating intent ('List all') and adds the concrete scope of '45+' libraries, but does not explicitly confirm absence of side effects or mention any permission or error behavior.
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 a single concise sentence that leads with the action and resource, then states the optional filter. There is no redundant or filler content, and every phrase 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 simple list tool with one optional parameter, full schema coverage, and an output schema, the description is sufficient. It tells the agent exactly what the tool returns access to and how to narrow results, without needing extra detail.
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 input schema already describes the only parameter with 100% coverage ('Optional category filter string'), so the description adds marginal semantic value by repeating the filtering idea. A baseline of 3 is appropriate because the schema fully handles parameter documentation.
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 ('List'), a resource ('documentation libraries'), and a scope ('all 45+', 'optionally filtered by category'). This distinguishes it clearly from sibling tools like get_docs and search_docs_multi, which target retrieval of docs rather than enumeration of libraries.
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 clearly conveys the primary usage context: enumerating the available libraries and optionally narrowing by category. It does not explicitly name alternatives or exclusion criteria, but the purpose is unambiguous enough for an agent to know when to call it.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.