pyfastmail-mcp

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 states the action ('Move or rename') but doesn't mention permissions required, whether the operation is atomic, what happens if the destination exists, if it works across folders or only within the same parent, or any rate limits. The description is minimal and lacks critical behavioral context for a mutation tool.

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 concise with two sentences: one stating the purpose and one listing parameters with examples. It's front-loaded with the core action. The parameter explanations are brief but clear, though the structure could be slightly improved by integrating the examples more seamlessly.

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 this is a mutation tool with no annotations, 2 parameters with 0% schema coverage, and an output schema (which reduces the need to describe return values), the description is minimally adequate. It covers the basic purpose and parameters but lacks behavioral details like error conditions, permissions, or cross-folder capabilities, which are important for a move/rename operation.

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 0%, so the schema provides no parameter documentation. The description adds basic semantics by explaining that 'source' is the source path and 'destination' is the destination path with examples, which covers the core meaning. However, it doesn't clarify path format constraints (e.g., absolute vs relative), special characters, or validation rules, leaving gaps.

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 ('Move or rename') and resource ('a file or folder on Fastmail Files (WebDAV)'), making the purpose immediately understandable. It doesn't explicitly differentiate from sibling tools like 'files_rename' (which doesn't exist) or 'mail_move_email', but the domain specificity ('Fastmail Files') provides some implicit 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?

No guidance is provided on when to use this tool versus alternatives. While sibling tools exist for mail movement ('mail_move_email'), there's no mention of when to choose files_move over other file operations like 'files_upload' or 'files_delete', nor any prerequisites or constraints for using this tool.

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