Flag / unflag emails

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

Annotations already indicate non-read-only, idempotent, and non-destructive behavior. The description adds detail about supported flag types and custom flags via add_flags/remove_flags, which is consistent with annotations and provides useful context.

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, front-loaded with the main action, and efficiently lists supported flags and custom flag usage. No unnecessary words.

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 tool with 5 parameters and no output schema, the description is incomplete. It does not mention success/failure behavior, return values, or the default mailbox value. While it covers the core flagging action, it lacks sufficient context for an agent to use it reliably.

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 description adds minimal meaning beyond the input schema. It clarifies the 'custom' action usage for add_flags/remove_flags, but does not describe 'uid' or 'mailbox' meaning, which are also missing from schema descriptions. Schema coverage is 60%, but the description fails to compensate for gaps.

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 'Toggles per-message flags' and lists supported flags. It distinguishes this tool from sibling tools like proton_move_email, proton_delete_email, etc., which handle different operations.

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 does not explicitly say when to use this tool versus alternatives, but the context of sibling tools makes it clear that this is for flagging operations. It lacks guidance on when not to use or specific prerequisites.

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