Email Get Attachment

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the mutation safety profile. The description adds concrete behavior: it writes to disk when save_dir is provided (returning a path) and otherwise returns inline content (with type-specific handling). This goes beyond the annotations by explaining the side effect of saving a file, which is a meaningful addition.

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 two sentences with zero filler. The primary purpose is front-loaded, followed by a concise explanation of the two operating modes. Every sentence contributes essential information, and the structure is easy to parse.

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?

For a tool without an output schema, the description adequately explains return values (path, inline content with type-specific handling). It covers the both modes of operation and implicitly states the core use case. No critical information required for calling it correctly is missing.

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 100%, so parameters are already well-documented. The description adds value by explaining the semantic distinction of save_dir (disk vs inline) and the return format (path vs image vs embedded resource). This supplements the schema's basic field definitions, making the tool's behavior clearer for an agent.

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 specific verb and resource: 'Download an email attachment.' This unambiguously identifies the action and distinguishes it from siblings like email_get_message (which retrieves the full message) and email_get_messages. The two modes (save to disk vs inline) are briefly noted, further clarifying scope.

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?

The description provides conditional guidance on when to use save_dir versus inline return, which directly informs selection of parameters. However, it does not explicitly contrast with alternative tools or state when not to use this tool. Since the purpose is self-evident and the mode decision is clear, this is helpful but not exhaustive.

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