pyfastmail-mcp

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

With no annotations provided, the description carries full burden for behavioral disclosure. It mentions the WebDAV context and default values but lacks critical details like whether this is a read-only operation, potential rate limits, authentication requirements, or error conditions. For a tool with zero annotation coverage, this leaves significant gaps in understanding its 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 efficiently structured with a clear purpose statement followed by parameter explanations. Every sentence adds value—none are redundant or verbose. The two-sentence format with bullet-like parameter details makes it easy to scan and understand quickly.

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 that an output schema exists (which handles return values), the description doesn't need to explain outputs. However, for a 2-parameter tool with no annotations, it should provide more behavioral context (like safety, permissions, or limitations) to be fully complete. The parameter explanations are good, but overall context remains somewhat thin.

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 provides meaningful explanations for both parameters beyond what the schema shows (0% coverage). It clarifies that 'path' defaults to root '/' and 'depth' has specific meanings ('0' for item itself, '1' for immediate children) with '1' as default. This compensates well for the schema's lack of descriptions, though it doesn't cover all possible edge cases.

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 ('List files and folders') and the resource ('at a WebDAV path on Fastmail Files'), making the purpose immediately understandable. However, it doesn't differentiate from sibling tools like 'files_get' or 'files_upload', which would require a more specific scope statement to earn a 5.

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?

No guidance is provided on when to use this tool versus alternatives like 'files_get' (for retrieving specific files) or 'files_upload' (for adding files). The description only explains what the tool does, not when it's appropriate relative to other file operations.

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