download_attachment

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 states that the tool returns base64-encoded data and MIME type, which is useful, but it does not clarify whether this operation is read-only, whether any safety checks are performed, or whether there are rate limits or size restrictions. Given the existence of a 'safe' variant, the lack of safety context is a notable omission.

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 long, front-loaded with the main action, and contains no fluff. Every word contributes value, and the return format is included without extraneous detail.

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 simple download function with two parameters and no output schema, the description states the purpose and return format adequately. However, it lacks any mention of how to obtain the required IDs (relying on schema hints), and it does not address the safety-sensitive nature of attachments, especially with a sibling 'safe' variant. This leaves the description slightly incomplete in context.

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 has 100% coverage, describing both parameters clearly. The description adds no additional semantic meaning beyond what the schema provides, so the baseline score of 3 is appropriate. It does not clarify formats, constraints, or relationships beyond the 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?

The description clearly states the verb ('Download') and resource ('a specific attachment from a Gmail message'), making the purpose unmistakable. It also specifies the return format (base64 data and MIME type). However, it does not explicitly distinguish from the sibling tool 'download_attachment_safe', which likely has a related but safer behavior, so it doesn't fully earn a 5.

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?

There is no guidance on when to use this tool versus its alternatives, such as 'download_attachment_safe' or 'list_attachments_with_safety'. The schema hints at needing an ID from 'read_email', but the description itself provides no context about prerequisites, exclusions, or choice criteria.

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