Apple Mail MCP Server

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

With no annotations provided, description carries full burden. Discloses output formatting behavior (indented format vs path format for nested mailboxes) and default values (include_counts defaults to True). Could improve by mentioning error cases or permissions requirements.

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 docstring format with clear Args/Returns sections. Front-loaded with core purpose. Returns section is slightly verbose but provides valuable formatting context. No redundant or wasted sentences.

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?

Appropriate for tool complexity (2 optional parameters, simple types). Despite 0% schema coverage, description fully documents inputs. Output schema exists per context signals, so detailed return documentation in description is supplementary rather than required.

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?

Excellent compensation for 0% schema description coverage. Provides detailed semantics for both parameters: account includes examples ('Gmail', 'Work') and null behavior, while include_counts explains its boolean purpose and default value.

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?

Clear verb-resource-scope combination: 'List all mailboxes (folders) for a specific account or all accounts.' Explicitly distinguishes from siblings like list_accounts (which lists accounts, not folders) and list_inbox_emails (which lists messages, not folders).

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 implied usage through parameter documentation (account filtering, include_counts), but lacks explicit when-to-use guidance versus alternatives like get_mailbox_unread_counts or list_accounts. No exclusions or prerequisites stated.

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