list_attachments

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), yet the description adds genuinely new behavior: a 40 MiB parsing ceiling, an explicit 'does not mark mail read' guarantee, and a security warning that filenames/contents are untrusted data. Those are non-obvious traits an agent would not get from the annotations alone.

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?

Purpose is front-loaded in the first clause, followed by constraint, safety, and security notes. Four sentences, each carrying distinct information, though the NAVER 40 MB aside is slightly verbose for the value it adds.

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 usefully enumerates the return fields (indexes, names, sizes, hashes) and discloses the parsing limit and read-state guarantee. It is nearly complete for a read-only listing tool; only pagination or large-attachment behavior is unaddressed.

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 only 33% – uid_validity is documented in-schema but uid and mailbox are not. The description merely restates the three parameter names without adding format, default, or semantics (e.g. that mailbox defaults to INBOX or how uid is sourced), so it fails to compensate for the low 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?

States a specific verb ('List') plus the exact resource and payload (attachment indexes, names, sizes, SHA-256 hashes) scoped to a message identified by mailbox/UID/UIDVALIDITY. The metadata-only framing implicitly separates it from download_attachment and get_email, so an agent can route correctly without opening a schema.

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 explicit when-to-use or when-not-to-use statement and no named alternative. The only hint is that it returns metadata rather than content, which an agent must infer to prefer it over download_attachment. No prerequisites or sequencing are given.

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