Apple Mail MCP Server

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

Without annotations, the description carries the full disclosure burden. It successfully documents the safety limit (default max_moves=50) and preview behavior (dry_run), but omits critical mutation details such as whether moves are reversible, error handling when destinations don't exist, or thread vs. individual email handling.

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?

Well-structured with clear sections (purpose, usage hints, Args, Returns) and front-loaded core functionality. The length is necessarily extended to compensate for schema deficiencies, but every sentence adds value—either explaining a parameter or clarifying usage patterns.

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 presence of an output schema, the brief return description ('Confirmation message with details') is sufficient. The description adequately covers the complex parameter set (10 params) and primary use cases (archiving, filtered moving). Minor gaps remain regarding error states and edge case handling.

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?

Fully compensates for 0% schema description coverage by documenting all 10 parameters in the Args section with specific examples (account: 'Gmail', 'Work'), format guidance (to_mailbox: use '/' separator for nesting), and behavioral notes (subject_keywords: 'matches any keyword'). This provides essential semantic context missing from the structured schema.

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 opens with a precise action statement: 'Move email(s) matching filters from one mailbox to another,' specifying the verb (Move), resource (emails), and scope (mailbox-to-mailbox with filtering). It clearly differentiates from sibling tools like search_emails (which only finds) or compose_email (which creates).

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?

Provides concrete usage patterns including 'Use dry_run=True to preview matches without moving' and specific guidance for archiving workflows ('For archiving to "Archive", just set to_mailbox="Archive"'). Lacks explicit contrast with alternatives like search_emails, but offers strong contextual guidance for key parameters.

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