download_attachment

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

With no annotations provided, the description carries the behavioral burden and does so well: it states the side effect (writes bytes to out), the return shape ({path, bytes_written}), and the explicit non-behavior (bytes are never returned inline). It stops short of disclosing overwrite behavior or access requirements, but the core action is transparent.

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 compact and front-loaded, opening with the main purpose and adding two tightly scoped behavioral notes. Every sentence earns its place and there is no redundant wording.

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 3-parameter tool with an output schema, the description covers the primary action, destination, return shape, and inline-return behavior. It is less complete on sourcing the required IDs and on usage context, yet the sibling set and tool name make the overall role reasonably clear.

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 only 33% (only `out` is documented), and the description does not compensate by defining `message_id` or `attachment_id` or explaining where they come from. It does clarify that `out` is the write destination, but two required parameters remain semantically implicit.

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 uses a specific verb ('Download') with a definite resource ('message attachment') and destination ('local file path'). It cleanly distinguishes this tool from sibling tools, which all concern filters, drafts, or raw messages rather than 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 intended use is implied by the action itself: call this when you need attachment bytes written to a local file. However, there is no explicit guidance about when not to use it, how to source message_id/attachment_id, or how it relates to siblings like get_raw_message.

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