insync_download_attachment

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

Annotations already declare readOnly/non-destructive/openWorld, and the description adds real deployment-dependent behavior: local installs write to disk and return a path, hosted servers return inline bytes, and all traffic flows through the portal rather than direct storage. It adds no auth, quota, or failure-mode detail, so it earns a 4 rather than 5.

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?

Four short sentences, each carrying distinct information: what it fetches, how to identify it, what comes back, and how the transfer is routed. The core action is front-loaded with zero filler.

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?

With no output schema, the description correctly covers return-value variability (file path vs inline bytes), which is the main thing an agent needs to interpret results. Minor gap: no mention of error behavior or what happens when the index is out of range.

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 coverage is 100% so the baseline is 3, but the description reinforces the index's meaning as a 0-based position sourced from insync_list_attachments and explains why output_dir only matters on local installs. That adds marginal value beyond the already-thorough 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?

States a specific verb and resource: 'Download one file attached to a secure message,' and clarifies single-file scope with the attachment identified by master id plus index. It implicitly separates itself from insync_download_document by scoping to message attachments, though it doesn't name that sibling as the alternative.

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?

Explicitly tells the agent where the two required inputs come from ('master id ... from insync_list_messages', 'index ... from insync_list_attachments'), giving a clear call sequence. It stops short of stating when not to use it or how it differs from insync_download_document.

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