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

With no annotations, the description fully discloses critical behaviors: it never returns bytes/base64, parsing runs in a sandboxed process with limits, type detection uses leading bytes rather than declared type, and returned message text is wrapped in an untrusted-content marker. This is exceptional transparency beyond what any annotation could provide.

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 dense but every sentence adds unique value: the contents list, format limitations, the no-bytes policy with rationale, sandboxing details, type-mismatch handling, and trust boundaries. It is front-loaded with the most important information and contains no fluff.

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 a single parameter, no annotations, and no output schema, the description covers everything an agent needs: what is returned, what is not returned, safety mechanisms, and how to interpret the data. There are no significant gaps for correct invocation.

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?

The input schema already fully documents the lone parameter 'key'—its origin, stability, and rejection of Apple row numbers. The tool description adds no additional parameter-level meaning, so the baseline score of 3 applies due to 100% schema coverage.

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 that the tool returns attachment metadata (name, part id, type, size) and optionally bounded extracted text, while explicitly excluding PDFs/images from text extraction. This distinguishes it from sibling tools like get_email_body or get_emails by focusing specifically on attachments.

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 gives clear context: use this tool when you need attachment metadata or extractable text. It also states when not to rely on it—PDFs/images yield no text, and file bytes/base64 are never returned. It does not name alternative tools explicitly, but the boundaries are evident.

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