pyfastmail-mcp

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

No annotations are provided, so the description carries the full burden. It states the tool creates a folder but does not disclose behavioral traits such as whether it overwrites existing folders, requires specific authentication, has rate limits, or returns error codes. This leaves significant gaps for an agent to understand the tool's 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 appropriately sized and front-loaded, with the main purpose stated first and parameter details following. The two sentences are efficient, though the parameter explanation could be slightly more integrated into the flow.

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 moderate complexity (a single-parameter mutation tool), no annotations, and the presence of an output schema (which handles return values), the description is minimally complete. It covers the basic purpose and parameter but lacks behavioral details and usage context, leaving room for improvement.

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 description adds minimal semantics beyond the input schema, providing an example ('/Documents/NewFolder') for the 'path' parameter. However, with 0% schema description coverage and only one parameter, this is adequate but not comprehensive—it doesn't explain path constraints or format rules beyond the example.

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 action ('Create a folder') and the resource ('on Fastmail Files (WebDAV)'), making the purpose unambiguous. However, it does not explicitly differentiate from sibling tools like 'files_upload' or 'files_move', which also involve file operations but for different purposes.

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 no guidance on when to use this tool versus alternatives. It lacks context about prerequisites (e.g., permissions), exclusions (e.g., cannot create folders in certain paths), or comparisons to siblings like 'files_list' for checking existing folders.

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