Apple Mail MCP Server

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

Discloses key behavioral traits not in annotations: auto-creation of intermediate path segments ('each segment is created if needed') and return value format ('Confirmation with the new mailbox path'). Missing error handling details (e.g., behavior if mailbox exists) which would be helpful given zero annotation coverage.

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?

Excellent structure with clear Args/Returns sections. Front-loaded purpose statement. Every sentence adds value: examples illustrate valid inputs, slash-handling explains behavior, return description sets expectations. No redundancy.

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?

Complete for a 3-parameter creation tool. Despite 0% schema description coverage, narrative fully documents all parameters and their relationships. Return value is summarized appropriately (output schema exists for detailed structure).

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?

Comprehensive compensation for 0% schema coverage: provides concrete examples for account ('Gmail', 'Work'), explains name syntax including slash-handling behavior, and clarifies parent_mailbox optionality. Documents parameter interactions (mutual exclusivity patterns) not evident in 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?

Opens with specific verb+resource ('Create a new mailbox') and clarifies mailbox equals 'folder'. Clearly distinguishes from sibling tools like list_mailboxes (read vs. write) and compose_email (message vs. folder operations).

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 explicit guidance on two valid usage patterns for nesting (parent_mailbox param vs. slash-separated name). However, lacks explicit 'when not to use' guidance or comparison to sibling alternatives like manage_drafts or list_mailboxes.

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