pyfastmail-mcp

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

No annotations are provided, so the description carries full burden. It mentions moving emails but doesn't disclose behavioral traits like whether this is a destructive operation (e.g., removes from source mailbox), requires specific permissions, handles errors (e.g., invalid mailbox names), or affects email threading. The description is minimal and lacks critical operational details.

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 front-loaded with the core purpose in the first sentence, followed by parameter details. It avoids unnecessary fluff and uses clear, direct language. However, the parameter explanations could be more integrated rather than listed as 'Args:', slightly reducing structural elegance.

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 no annotations, 0% schema coverage, but an output schema exists, the description is moderately complete. It covers the basic action and parameters but lacks behavioral context (e.g., side effects, error handling) and doesn't mention the output schema's role. For a mutation tool with sibling alternatives, more guidance and transparency would improve completeness.

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 descriptions. The description adds basic semantics: email_ids are 'JMAP email IDs to move' and mailbox_name is 'Name of the destination mailbox (case-insensitive)'. This clarifies data types and constraints (case-insensitivity), but doesn't explain format details (e.g., JMAP ID structure) 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 tool moves emails to a mailbox, specifying the action (move), resource (emails), and destination (mailbox). It distinguishes from siblings like mail_archive_email or mail_delete_email by focusing on relocation rather than archiving or deletion. However, it doesn't explicitly differentiate from mail_manage_email_labels which might also affect email organization.

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 mail_archive_email or mail_manage_email_labels. The description lacks context about prerequisites (e.g., existing mailboxes) or typical use cases (e.g., organizing emails into folders). It simply states what the tool does without indicating appropriate scenarios.

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