Apple Mail MCP Server

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 successfully documents the return value structure ('names and sizes') and the default value for max_results, but omits critical operational details like which folders are searched, case sensitivity rules for the keyword, or behavior when no matches exist.

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?

Uses a standard docstring format (summary + Args + Returns) that is appropriately sized and front-loaded. Every sentence conveys necessary information; the structure efficiently separates input specifications from output expectations without 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?

Given the tool's moderate complexity (3 primitive parameters) and the existence of an output schema, the description provides sufficient context. It compensates adequately for the schema's lack of descriptions through its Args section, though it could benefit from noting edge cases or search scope limitations.

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. The Args section documents all three parameters with clear semantics and provides helpful examples for the 'account' parameter ('Gmail', 'Work', 'Personal'). It also surfaces the default value (1) for max_results which isn't visible in the schema properties section provided.

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 lists attachments filtered by subject keyword, distinguishing it from sibling tools like 'save_email_attachment' (which downloads) and 'search_emails' (which likely returns full messages). However, it doesn't explicitly clarify the difference from 'list_inbox_emails' which may overlap in functionality.

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 provided on when to use this tool versus alternatives like 'search_emails' or 'save_email_attachment'. The agent must infer that this is for discovery/inspection of attachments without downloading them, based solely on the verb 'List'.

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